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4.1 Atoms
4.3 Elements are arranged in groups in the periodic
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4.6 Isotopes
4.7 The half-life of isotopes can be used to date objects
4.8 Challenge:
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5.1 Mass
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5.3 Balanced chemical equations show the rearrangement
5.4
5.5 Challenge: Modelling
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5.7 Exploring
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iv Oxford Science 9 Western Australian Curriculum Oxford University Press
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Introducing Oxford Science 9 Western Australian Curriculum (Second edition)
Congratulations on choosing Oxford Science 9 Western Australian Curriculum (Second edition) as part of your studies this year!
Oxford Science 9 Western Australian Curriculum (Second edition) has been purpose-written to meet the requirements of the Australian Curriculum version 9.0. It includes a range of flexible print and digital products to suit your school and incorporates a wide variety of features designed to make learning fun, purposeful and accessible to all students!
Key features of Student Books
The Science toolkit is a standalone module that explicitly teaches important Science inquiry skills. The Aboriginal and Torres Strait Islander Histories and Cultures cross-curriculum priority is addressed in both standalone lessons and within other lessons.
In each core lesson:
• a concept statement summarises the key concept in one sentence
• key ideas are summarised in succinct dot points
• key terms are bolded in blue text, with a glossary definition provided in the margin a set of check your learning questions are aligned to the learning intentions for the lesson.
Lesson 1.3
Planning and conducting investigations
Lesson 5.9 Experiment: Electrolysis of copper sulfate
Science as a human endeavour lessons explore real world examples and case studies, allowing students to apply science understanding.
The Test your skills and capabilities section provides scaffolded opportunities for students to apply their science understanding while developing skills and capabilities.
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Practical activities appear within each module, directly after the core lesson they relate to. Additional activities are provided through Oxford Digital.
Challenges, Skills labs and Experiments provide students with opportunities to use problem-solving and critical thinking, and apply science inquiry skills.
For a complete overview of all the features and benefits of this Student Book: > activate your digital access (using the instructions on the inside front cover of this book) and click on “Introducing Oxford Science 9 Western Australian Curriculum (Second edition) ” in the “About this course” menu.
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There’s also a range of unique features designed to improve learning outcomes.
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Module 7 Particles and waves
Overview
Energy transfer can be described using wave and particle models. Waves (electromagnetic and mechanical) have the properties of amplitude, wavelength, frequency and speed. Sound energy travels in waves, and its volume and pitch are linked to amplitude and frequency. Heat transfer is explained by the particle model and includes conduction and convection. The particle model can also be used to explain static electricity and electrical current, including voltage, conductors and insulators. Electromagnetic radiation, such as light, is understood through both wave and particle models and is used in radar, medicine and communication.
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Lessons in this module
Lesson 7.1 Vibrating particles pass on sound (page 266)
Lesson 7.2 Sound can travel at different speeds (page 271)
Lesson 7.3 Light (page 275)
Lesson 7.4 Light reflects off a mirror (page 278)
Lesson 7.5 Experiment: Reflection from plane mirrors (page 281)
Lesson 7.6 The refraction of light (page 284)
Lesson 7.7 How the eye works (page 288)
Lesson 7.8 Different wavelengths of light are different colours (page 291)
Lesson 7.9 Experiment: What colour is it? (page 293)
Lesson 7.10 The electromagnetic spectrum has many uses (page 294)
Lesson 7.11 Experiment: What is the wavelength of a microwave? (page 297)
Lesson 7.12 Review: Particles and waves (page 298)
Learning intentions and success criteria
Lesson 7.1
Vibrating particles pass on sound
Key ideas
→ Sound is caused by the vibration of particles moving in a longitudinal wave.
→ One wavelength is the distance between one compression of air particles and the next, and the time taken for a wave to complete a cycle is called the period.
→ The distance an air particle moves is called the amplitude.
compression part of a sound wave where air particles are forced close together
rarefaction a reduction in density; refers to the part of a sound wave where air particles are forced apart
longitudinal wave a type of (sound) wave where the particles move in the direction of travel of the wave
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compression wave (also known as longitudinal wave) a type of (sound) wave where the particles move in the direction of travel of the wave
amplitude the distance a particle in a wave moves from its position of rest
→ The number of waves passing a point each second is the frequency of the wave.
→ An object's resonance is caused by vibrations that match the frequency of another object.
→ Resonance is the natural tendency of objects to vibrate more vigorously at some frequencies than others.
→ We are able to hear things because the ear has an auditory nerve that turns vibrations in the air into a signal that the brain interprets.
→ There are different types of hearing loss depending on which part of the ear is not functioning properly, and they include conductive and sensorineural hearing loss.
Sound waves
What causes sound? We know that sound energy travels because sound can often be heard a long way from its source.
Consider the example of playing a drum. When we hit the drum skin, it vibrates (moves up and down). The kinetic energy of the vibrations is transferred to the surrounding air particles, pushing them closer together in one place and forcing them further apart in another. In this way, the air around the drum is made to vibrate too. This causes particles further away to vibrate, and so on, until the air close to your ears eventually vibrates and causes your eardrum to vibrate too. And that’s when you hear the sound.
Describing sound
You can sing high. You can sing low. You can talk in a funny voice if you want to because you can alter the number of vibrations coming from your vocal cords every second.
As air particles vibrate, the region where the particles are forced close together is called a compression, and the less dense region where the air particles are further apart is called a rarefaction. This creates sound waves that travel as a longitudinal wave or compression wave. Air particles do not travel to your ear. Instead, the air particles move back and forth, parallel to the wave, as the vibration passes through the air. The distance a particle of air moves from its normal position is called the amplitude of the wave (Figure 1).
Sound waves with a large amplitude cause the air particles to move with greater kinetic energy. This makes the sound feel louder to our ears. An example of this is when musicians use amplifiers to increase the loudness of their music. Amplifiers increase the distance that air particles move during compression and rarefaction.
The distance between two compressions (crests) or two rarefactions (troughs) can be close together or far apart. The distance between the start of one crest and the start of the next is called the wavelength (or the start of one trough and the start of the next), and the time taken for this to occur is known as the period (Figure 2). Short wavelengths mean more vibrations hit your eardrum each second.
When the compressions travel close together, they are considered more frequent. The number of waves that pass a point each second is called the frequency (f ) of a wave. Frequency is measured in the unit hertz (symbol Hz).
Direction of sound waves
Rarefaction Compression
Figure 1 A longitudinal wave is created from compressions and rarefactions
Amplitude
Wavelength Trough Crest
Figure 2 A wavelength is the distance between two crests or two troughs.
To calculate the frequency of a wave, you use the period of the wavelength, in seconds (T ), and this formula: f = 1 T
Compression
Air particles
Sound wave Rarefaction
wavelength the distance between two crests or troughs of a wave
period (in relation to physics) the time taken between two crests or troughs of a wave
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Air particles
Rarefaction
Wavelength
Compression
3 A sound wave is produced when (A) a drummer hits a drum skin and (B) a person speaks.
frequency the number of waves that pass a point every second; measured in hertz hertz the unit used to measure frequency; symbol Hz
Figure
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resonance when a vibrating object causes another object to vibrate at a higher amplitude
resonance frequency the natural frequency where a medium vibrates at the highest amplitude
The frequency of a wave can also be calculated if you know the speed of the wave, in metres per second (m/s), the wavelength, in metres (m), and this formula:
frequency = wave speed (m/s) wavelength (s) f = v λ .
A sound wave moves out in all directions from the place where the vibration began (Figure 3). As the waves move further away from their source, they lose energy and eventually fade out. As neighbours will confirm, the closer you live to a drummer, the louder they seem!
Pitch
We hear different frequencies as different pitches. For example, a soprano sings the high notes in an opera. These notes are high pitched. The sound waves for these notes have very short wavelengths and therefore high frequency (Figure 4). A deep bass singer is able to sing very low-pitched notes. These notes have long wavelengths, and few of them can pass a point each second. Therefore, they have a low frequency.
Wave disturbance
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Wave shape for a low-pitched sound
Wave disturbance
Wave shape for a high-pitched sound
Figure 4 The difference between a high-pitched and low-pitched sound
Resonance and its applications
When an object vibrates, it can cause another object to vibrate with a maximum amplitude. This is known as resonance. An object’s resonance frequency relates to the natural frequencies at which it vibrates at maximum amplitude.
One of the advantages of resonance is its ability to increase the amplitude of vibrations, hence amplifying sound, signals or energy in different systems. An application of the resonance of sound is that of musical instruments. Instruments create music by creating vibrations in the form of sound waves. Resonance is useful in this context because it amplifies the sound waves to create louder sounds. Resonance also helps when tuning an instrument to ensure it operates at the optimum frequency.
Can a singer break a glass?
Yes, in theory, but it’s not easy! If the singer can match the resonance frequency of the glass and sing with enough intensity (not just volume, but focused energy), the glass will start to vibrate. If the singer holds that note long enough, the vibrations can grow stronger and stronger until the glass shatters.
In 2005, the TV show MythBusters tested this idea. They found that it is possible to break a glass using a high-pitched sound, especially when the sound is amplified using microphones and speakers. They also tested it without amplification. After 20 attempts, singer Jamie Vendera managed to break a glass by singing at 556 Hz (a high note) and 105 decibels (a very loud sound). So, while it is rare, it can happen under the right conditions.
Bridge design
Resonance is also important in engineering, especially when designing bridges. Things like wind, earthquakes and even traffic can cause a bridge to vibrate. If those vibrations match the bridge’s resonance frequency, the vibrations grow stronger and more dangerous. In extreme cases, it can cause the bridge to collapse.
To prevent this, engineers:
• test the natural frequencies of bridges before they’re built
• design bridges to avoid resonance from common forces like wind and traffic
• add dampers, which are special devices that absorb energy and reduce vibrations (Figure 5A).
In America in 1940, the Tacoma Narrows Bridge collapsed because wind caused it to vibrate at its natural frequency. The vibrations grew stronger and stronger until the bridge broke apart (Figure 5B).
How we hear
In order for us to process sound, several things need to happen (Figure 6).
1 Sound is created by someone talking or playing music. This causes the air particles to vibrate.
2 T hese vibrations travel through the air as mechanical energy (moving particles).
3 T he pinna (outer ear) collects the sound waves, which travel down the ear canal to the eardrum.
4 T he eardrum vibrates, causing three tiny bones to vibrate.
Pinna
Auditory nerve
Ear canal
Eardrum
Figure 6 Structures of the ear that allow sound waves to be converted into an electrical signal that the brain can process
Figure 5 (A) A damper on the Millennium Bridge in London, UK. (B) In 1940, the Tacoma Narrows Bridge in Washington, USA, collapsed due to resonance caused by wind.
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5 T hese bones amplify the vibrations, which reach the cochlea, which is filled with fluid and tiny hair cells.
6 T he tiny hair cells convert mechanical energy into electrical signals.
7 T he electrical signal travels along the auditory nerve to the brain, which interprets it as sound.
Hearing problems
Hearing loss can occur when any part of the ear or the auditory (hearing) system is not functioning properly. This includes conductive and sensorineural hearing loss.
• C onductive hearing loss occurs when the mechanical energy (sound vibrations) cannot pass through the outer or middle ear properly. This can be due to earwax buildup, damage to the middle ear or fluid in the middle ear. As a result, less mechanical energy reaches the cochlea, so sounds may seem softer and be harder to hear.
• S ensorineural hearing loss occurs when the conversion of mechanical energy into electrical signals is reduced, meaning the brain receives a weaker signal, which makes sounds seem quieter or unclear. This is the most common type of hearing loss that involves the inner ear or auditory nerve and can be due to ageing, exposure to loud noise or genetic conditions.
Check your learning 7.1
Check your learning 7.1
Retrieve
1 Describe how the particles in air are arranged in: a compression b rarefaction.
2 Define the following two characteristics of a sound wave. a Period b A mplitude
3 Identify the types of hearing loss.
4 Identify the part of the ear that collects sound waves.
Comprehend
5 Work with a partner. Explain to your partner how the sound waves created by hitting a cymbal reach your ears. Use the following terms: compression, rarefaction, sound wave, spread out, air particles and ear. Write down your description.
DRAFT
9 Ca lculate the frequency of a wave that has a period of 0.006 seconds.
10 Ca lculate the frequency of a wave that travels at a speed of 330 m/s and has a wavelength of 3 metres.
Analyse
11 O f the two springs shown in Figure 7, identify which one demonstrates: a lower frequency b shor ter wavelength.
6 E xplain how the air moves when an opera singer sings a note.
7 Describe resonance, and how it relates to sound.
8 E xplain how conductive hearing loss affects the way sound is processed in the ear.
Figure 7 Springs
12 I magine you have three tuning forks of frequencies 250, 500 and 1,000 Hz. Identify the frequency that would have the: a lowest pitch b highest pitch.
13 C ontrast the frequency and pitch of sound.
14 Explain what would happen if the cochlea were damaged. Describe how this would affect hearing.
Apply
15 I magine that a student is listening to music at a very high volume every day. Predict what type of hearing loss they might develop and explain why.
16 Determine if a hearing aid would help someone if their auditory nerve was damaged. Justify your answer.
Lesson 7.2
Sound can travel at different speeds
Key ideas
→ The speed of sound through air at sea level and at 20°C is approximately 340 m/s.
→ The temperature and material through which sound travels will affect the speed of sound.
→ At higher temperatures, particles are compressed more easily because of their higher kinetic energy.
→ The more closely packed the particles, the faster the sound wave travels.
→ Sound can be reflected, and this property of sound is used in sonar, echolocation and medical imaging.
Sounds of silence
If you have ever played an instrument, you may have been told by your family to “keep the noise down!”, especially for loud instruments such as the drums or wind instruments such as the trumpet and saxophone. Is there a place where you could play your instrument as loud as possible without it being heard? Yes, there is, but it isn’t easy to get to, and you would need to be wearing a special suit to survive!
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Yes, it is outer space! The reason why no-one, including yourself, could hear the instrument being played in space is that sound needs a medium (a solid, liquid or gas) to move through. The particles pass energy to each other, creating compressions and rarefactions, which create sound waves. In space, these particles are too far apart to pass the energy on; hence, why no sound can be heard (Figure 1).
Learning intentions and success criteria
medium a substance or material through which light can move
Figure 1 In outer space, there are so few particles of gas and they are so far apart that they cannot be compressed. As a result, outer space is silent.
echo sound that is reflected off a surface
Speed of sound
The speed of sound in a medium is dependent on the space between the particles and how far they can move. Using our understanding of the states of matter, the particles in water will be much closer to each other when compared to air. Water particles can move and compress more easily than air particles, meaning that sound will travel more easily through water than air. Sounds also travel faster in most solids because their particles are packed closely together.
Under the right conditions, the low-frequency song of a whale can travel over 1,000 kilometres. This is the reason that whales sing their tunes under the water rather than on the surface. For humans on land, sound travels through the air at a speed of 340 m/s (assuming we’re at sea level at 20°C) and can travel anywhere between 10 and 1,000 metres, depending on the conditions.
The speed of sound also depends on the temperature of the material it is travelling through. At higher temperatures, particles have more kinetic energy, which means they are moving and vibrating faster. Because of this, they can transfer energy more quickly to nearby particles, allowing the sound wave to move faster through the medium (Table 1).
Echoes
Table 1 Speed of sound in different mediums at different temperatures
DRAFT
sonar the detection of the location of objects through the use of sound waves
Although sound travels faster through solids than through air, sometimes a sound wave in the air will bounce off the surface of a solid instead of entering it. This usually happens when the solid is very dense and has a flat, hard surface facing the direction of the sound. You may have noticed this when you shout from the top of a mountain into a valley. The sound travels through the air, hits the surface of another nearby mountain, and reflects back. When the reflected sound reaches your ears, you hear an echo
If the surface is not flat and hard, for example, if it is soft or has lots of lumps and bumps, the sound wave is either absorbed or scattered. This means the sound doesn’t reflect clearly, and you won’t hear an echo. That’s why music recording studios often have walls with soft materials or irregular surfaces, to absorb or break up sound waves and prevent echoes or unwanted sound reflections (Figure 2).
Sonar and its applications
Figure 2 Recording studios and movie theatres make use of soft materials or irregular surfaces to prevent echoes or unwanted sound reflections.
Sonar can be used to determine the exact location of an object by sending out sound waves and recording the time it takes for the sound wave to reflect off an object. This, coupled with knowing how fast the sound wave travels in water, means the distance to the object can be calculated, with objects further away taking longer to reflect the sound wave.
This was very useful in World War 1, where sonar was used to detect German submarines under water.
Seismic surveying
Sonar is widely used today and can help map the ocean floor, check the depth of water, locate schools of fish and search for navigational hazards underwater (Figure 3).
Mining and energy companies also use sonar as part of seismic exploration and surveying to search for new oil or mineral deposits. This method is much more effective than randomly drilling into the ground. To collect the required data:
1 A controlled blast or vibration is set off at the surface.
2 T he shock waves travel through the ground and reflect off different underground layers.
3 Detectors (called geophones or hydrophones) pick up the reflected waves.
4 A computer uses this data to create an image of the underground structure, showing where potential deposits might be.
The way shock waves reflect depends on the type of material underground. For example, rock, oil and gas will reflect the waves differently (Figure 4).
Figure 3 Sonar is used to map volcanoes on the ocean floor.
Figure 4 How seismic exploration works.
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echolocation a method of using sound waves to determine the distance and direction of an object
Echolocation
Bats, dolphins and deep-sea fish are some of the animals that utilise echolocation (Figure 5). These animals move and hunt in the dark and rely on echolocation to navigate through their environment and determine the location and distance of objects. They do this by producing a sound and then interpreting the echoes that return.
For example, some birds, such as oilbirds and cave swiftlets, emit clicks to navigate, while some shrews (a mouse-like mammal) use ultrasonic squeaks to map their surrounding and find food. Hedgehogs use ultrasonic whistles. Some humans, particularly those who are visually impaired, can navigate their surroundings by listening to echoes bouncing off surfaces.
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Ultrasound
Ultrasounds, also called sonograms, capture information in real-time using high-frequency sound waves. The images that are captured can show, for example, the development of a baby, the blood flow through the circulatory system and the movement of internal organs (Figure 6).
Ultrasounds are also used to treat soft-tissue injuries. The sound waves cause the tissue to vibrate, which generates heat. This heat can help increase blood flow to the area, relieve pain and reduce muscle spasms. This helps speed up the healing process, reduce inflammation and stimulate collagen production, which is important for tissue repair.
Figure 5 A bat uses echolocation to determine how far away an insect is.
Figure 6 Ultrasounds are used to look at organs for signs of damage.
Check your learning 7.2
Check your learning 7.2
Retrieve
1 Identify which of the following materials will allow sound to travel the fastest.
A Water
B Lead
C Air
D Glass
2 Define an echo.
3 E xplain the term “sonar”.
Comprehend
4 Describe how sound moves through a liquid.
5 E xplain why we would not hear the noise of an explosion on Earth if a nearby star were to explode.
6 Describe the difference between sonar and echolocation.
7 Describe how temperature affects the speed of sound in the air.
Analyse
8 C ompare sonar used in submarines with seismic surveying used in mining.
9 E xplain why echoes are clearer in a canyon than in a forest.
Apply
10 E choes occur when sound bounces off smooth surfaces. Identify which of the following is most likely to produce a loud echo. Justify your answer (by describing how sound moves in each case and deciding which will produce the loudest echo).
Lesson 7.3
Light
Key ideas
DRAFT
a Talking in a furnished, carpeted room
b Singing in a tiled shower
c Yelling across an open field
11 A bat uses echolocation to hunt insects. Explain how fog or rain might affect its ability to locate prey.
12 E xplain how seismic surveying could help a geologist find oil underground.
13 A hospital technician is using ultrasound to examine a patient’s muscles. Explain what properties of sound make this possible.
→ Light travels as an electromagnetic wave with a transverse motion.
→ Electromagnetic waves in a vacuum travel at the same speed.
→ Light also behaves like a particle called a photon.
Light and the electromagnetic spectrum
Like sound, light is a form of energy that can behave like a wave. There are different types of light (Figure 1), and together, they make up the electromagnetic spectrum. The electromagnetic spectrum includes the energy that provides music on your radio, the picture on your television and the heat to cook popcorn in your microwave.
Learning intentions and success criteria
electromagnetic spectrum the full range of frequencies for all waves
transverse wave a type of (light) wave where the vibrations are at right angles to the direction of the wave
We only see a small amount of this light energy. The different types of light have common features. They all travel at the same speed – the speed of light – but they have differences too. They have different frequencies and therefore different wavelengths.
Short wavelength, high frequency
DRAFT
Long wavelength, low frequency
Speed of light
Light waves travel extremely fast: 300,000 km/s in a vacuum. This value is known as the speed of light. Light waves can travel through other mediums, such as air, water and glass, where they slow down slightly.
The speed of light is much faster than the speed of sound, which is why you will always see the light from lightning before you hear the sound of thunder. Unlike sound waves, light waves don’t need a medium (solid, liquid or gas) in which to travel due to their electromagnetic nature. They don’t pass their energy from atom to atom like sound waves do. This means that different forms of light can travel through space to reach us on Earth.
Light as a wave
Light waves are different from sound waves. Sound waves exist as longitudinal waves – the vibrations of the air particles are parallel to the direction of travel of the wave.
Light is a wave made of invisible forces that wiggle up and down and side to side, all while the light moves forward. These wiggling parts are always at right angles to the direction light travels in (Figure 2). We call these transverse waves.
The distance between two crests or troughs on a transverse wave is called the wavelength. It is the same as the distance between any two consecutive matching points on the wave. At a different wavelength, the nature of the light wave changes. In the region of visible light, this change of wavelength is seen as different colours.
Visible light
Figure 1 The electromagnetic spectrum
Figure 2 Light is a transverse wave that has forces that wiggle at right angles to the direction light travels in.
Because light waves have different wavelengths, they also have different frequencies. As with sound waves, the frequency of a light wave is a measure of the number of waves that pass a point each second (unit Hz).
As the frequency becomes higher, more waves (with short wavelengths) pass a point each second. This means high frequencies have shorter wavelengths. Like sound, amplitude is a measure of how far a particle moves from its place of rest.
Particle or wave?
Experiments by early scientists showed two different ways that light behaves. In some experiments, light acted like a wave. In others, it behaved like a particle.
In 1905, Albert Einstein proposed that light is also made up of particles called photons. This idea came from his explanation of the photoelectric effect, where light hits a metal surface and knocks electrons off it (Figure 3). If light were only a wave, this observation wouldn’t make sense, because waves alone don’t have enough energy to knock electrons off metal.
Figure 3 Light waves on their own do not have enough energy to knock electrons off a metal surface, which meant something else was responsible. This led to the discovery of the photon, and that light can behave as a wave and as a particle.
Today, scientists agree that light behaves both like a wave and a particle. A photon can move in a wavelike way; it can reflect off surfaces and slow down when it travels through thicker materials, just like a water wave. But it can also travel through empty space on its own, like a tiny particle. That’s how sunlight can reach Earth through the vacuum of space.
1 R ecall the unit used to measure wavelength.
2 R ecall the speed of light in a vacuum.
3 Identify three types of electromagnetic waves other than visible light.
4 R ecall the name of the tiny particle that makes up light.
DRAFT
Comprehend
5 T he frequency of a wave is measured in units called hertz (Hz). Describe the relationship between a hertz and the unit of time, the second (s).
6 E xplain why you see lightning before you hear thunder.
7 E xplain why light can travel through space but sound cannot.
photon a particle that makes up light and other forms of the electromagnetic spectrum
8 Describe how the wavelength and frequency of light are related.
Analyse
9 C ompare sound waves and light waves.
10 Sound is a wave, but sound cannot travel through a vacuum (empty space). Light can travel in a vacuum. Contrast sound and light to explain these two statements.
Apply
11 Ca lculate the frequency of a light wave with a wavelength of 600 nm, using the speed of light as 300,000,000 m/s. (HINT: 600 nm is also the same as 600 × 10 -9 metres)
Learning intentions and success criteria
Lesson 7.4 Light reflects off a mirror
Key ideas
→ Light can travel through transparent objects and is blocked by opaque objects.
→ Translucent objects allow some light through.
Check the next lesson for a linked practical activity or experiment.
transparent allowing all light to pass through, so objects can be seen clearly
translucent allowing light through, but diffusing the light so objects cannot be seen clearly
→ When light is reflected off a mirror, the angle of incidence is equal to the angle of reflection (Law of Reflection).
→ The image in a mirror is called a virtual image.
Introduction
Light can reflect off a glass window, but most of the light is transmitted and passes through the window. This is because the glass in the window is transparent . Some types of frosted glass prevent us from seeing through them clearly. They are called translucent because they let some light through, but objects cannot be seen clearly. An opaque material is one that you cannot see through. However, if it is shiny enough or has a reflective coating, it can reflect the light and produce a clear image. The best example of this is a mirror.
The Law of Reflection
DRAFT
opaque not allowing light to pass through
image a likeness of an object that is produced as a result of light reflection or refraction
normal (in relation to light) an imaginary line drawn at right angles to the surface of a reflective or refractive material
Light always follows specific rules when it reflects off a surface, whether the surface is smooth or rough. This can be seen in Figure 2, where incoming light is reflected off a mirror.
• T he incident ray represents the incoming light and strikes the mirror.
• T he reflected ray leaves the mirror from the base of the normal at the same angle as the incidence ray.
• T he normal is an imaginary line that is drawn at 90° (perpendicular) to the mirror’s surface. It is usually drawn as a dotted line.
Angle of reflection
Figure 2 The angle of incidence (i ) and the angle of reflection (r) are the same when light reflects off a mirror.
Figure 1 Examples of (A) a transparent window, (B) a translucent window and (C) an opaque window
• T he angle of incidence is the angle between the incident ray and the normal.
• T he angle of reflection is the angle between the reflected ray and the normal.
An arrow is used to indicate which line is the incident ray and which is the reflected ray.
The Law of Reflection states that the angle of incidence (symbol i ) equals the angle of reflection (symbol r).
Types of mirrors
Plane mirror
When we look in a plane mirror (a flat mirror), we see a picture, or image, of ourselves. In the case of a plane mirror, the image is always a virtual image. This means it cannot be captured on a piece of paper or on a screen as a movie projector does.
Images in a plane mirror form when the light rays cross. This means images in a plane mirror are:
• t he same size as the object
• t he same distance from the mirror as the object is
Figure 3 The image in a plane mirror is virtual, laterally inverted, the same size as the object and the same distance from the mirror.
Curved mirrors are not as predictable as plane mirrors. They can change the size and nature of the object’s image (Figure 4B).
Concave mirrors curve inwards, like the inside of a spoon or a cave. They reflect light towards a focal point in front of the mirror. The type of image formed depends on how far the object is from the mirror, as seen in the ray diagram (Figure 5A).
angle of incidence the angle between an incident ray and the normal (a line drawn at right angles to a reflective surface) angle of reflection the angle between a reflected ray and the normal (a line drawn at right angles to a reflective surface) virtual image an image that appears in a mirror and cannot be captured on a screen
concave refers to a lens or mirror that is thinner in the centre than at the ends
focal point where light rays meeting after reflection or refraction
ray diagram a drawing used to represent the path of light reflecting off mirrors or travelling through lenses
Plane mirror
Figure 4 (A) Plane mirrors show the lateral inversion of what we look like. (B) Curved mirrors can show a distorted image of what we look like.
If the object is close to the mirror (between the mirror and the focal point), the image is:
• v irtual
• upright
• larger than the object.
If the object is further away (beyond the focal point), the image is:
• re al
• i nverted (upside down)
• smaller or larger than the object, depending on the distance.
An example of this is reflecting telescopes, which use concave mirrors to focus light from distant stars.
Convex mirrors
DRAFT
Convex mirrors curve outward, like the back of a spoon. They cause light rays to spread out, making them appear to come from a point beyond the mirror (Figure 5B). These mirrors always form images that are:
• v irtual
• upright
• smaller than the object.
This is typically seen in rear view mirrors on cars, which provide a wider field of view (Figure 6).
convex
Figure 6 The rear view mirror of a car is a convex mirror that makes images appear smaller than they actually are. That is why it’s important to check where a car is before changing lanes.
Figure 5 Ray diagrams of (A) a concave mirror where the object is beyond the focal point and (B) a convex mirror
Check your learning 7.4
Check your learning 7.4
Retrieve
1 Define the terms “transparent”, “translucent” and “opaque”, and identify one example of each.
2 R ecall one use each of convex and concave mirrors.
3 Describe the Law of Reflection.
4 R ecall the name of the imaginary line drawn at 90° to the surface of a mirror.
5 Determine if the images formed by convex mirrors are upright or inverted.
Comprehend
6 E xplain why light fittings are often translucent.
7 Define the normal, incident ray, angle of incidence, reflected ray and angle of reflection. Use a diagram to illustrate your definitions.
8 Describe a virtual image and provide an example of where you would see one.
9 E xplain why the image in a plane mirror is called a virtual image.
Lesson 7.5
10 E xplain why convex mirrors make objects appear smaller.
Analyse
11 C ompare the images formed by plane, concave and convex mirrors in terms of size, orientation and type (real or virtual).
12 A nalyse why convex mirrors are used for security and in car side mirrors.
13 A student claims that concave mirrors always make images bigger. Evaluate this claim using examples.
Apply
14 A l ight ray hits a flat mirror at an angle of 35° to the normal. Determine the angle of reflection.
15 C reate a ray diagram showing how light reflects off a plane mirror to form an image.
16 Use the Law of Reflection to explain how a periscope works.
Experiment: Reflection from plane mirrors
Aim
DRAFT
To investigate the Law of Reflection: the angle of incidence equals the angle of reflection
Materials
• Hodson light box kit
• Power supply
• Sheet of white A4 paper
• Plane mirror from light box kit
• Blu Tack
• Ruler
• Pencil
• P rotractor
Method
1 Rule a straight line in pencil centrally across the width of the A4 paper. The mirror surface will be placed along this line.
2 Use the protractor to construct a normal line at 90° in the centre of the first line.
3 Position the back edge of the plane mirror along the first pencil line. Keep it in place with Blu Tack.
4 Place the light box on a piece of white A4 paper.
5 Plug the light box into either the AC or DC sockets of a power supply. The voltage dial controls the brightness of the light globe.
6 Slide a single-slot former into the opposite end of the light box to where the mirror flaps are.
DRAFT
7 A im the incident ray at the centre of the mirror where the normal begins.
University Press
Oxford Science 9 Western Australian Curriculum
8 Use a sharp pencil to mark the incident and reflected rays with dots.
9 Move the light box to a different angle and aim another incident ray so that it hits the mirror at the same place as it did the first time. Mark the incidence and reflection rays by drawing arrows. Label the lines A.
10 Repeat steps 5-9 until five sets of lines are obtained. Label each set of lines B, C, D, etc.
Results
1 Remove the light box and rule lines to show the straight path of the incident and reflected rays.
2 Carefully use the protractor to measure the five angles of incidence and the five angles of reflection for each set of lines A, B, C, etc.
3 Move the protractor so that the 0° of the protractor is along the normal. Read the angle between the normal and each incident ray, and between the normal and reflected rays.
4 Record your results in a suitable table.
Discussion
DRAFT
1 E xplain why the back edge and not the front edge of the plane mirror should be lined up on the pencil line.
2 C ompare your angles of incidence to your angles of reflection. Explain how they support the Law of Reflection.
3 Identify two possible sources of error in this experiment.
4 Describe what happened when you directed the light at right angles to the mirror.
5 E xplain whether the Law of Reflection is still obeyed if the angle of incidence is 0°.
6 Describe at least three examples where you have observed the Law of Reflection in action.
Conclusion
Write a conclusion that summarises what you know about the relationship between the angle of incidence and the angle of reflection.
Learning intentions and success criteria
refraction the bending of light as a result of speeding up or slowing down when moving into a medium of different density refractive index a measure of the bending of light as it passes from one medium to another refracted ray a ray of light that has bent as a result of speeding up or slowing down when it moves into a more or less dense medium angle of refraction the angle between a refracted ray and the normal (a line drawn at right angles to a refractive surface)
Parallel-sided glass slab
Lesson 7.6 The refraction of light
Key ideas
→ Refraction is when light bends as it enters or leaves a medium.
→ Light entering a more optically dense medium bends towards the normal.
→ Light entering a less optically dense medium bends away from the normal.
→ Snell’s Law determines the refractive index of an unknown material.
→ Lenses allow light to diverge or converge.
Refraction
Refraction is the bending of light as it passes at an angle from one transparent medium into another. For example, light bends when it travels from air into water, or from water into air.
This bending of light can make objects appear distorted or shifted. You might have noticed this effect when looking at a spoon in a glass of water. The spoon appears bent or broken at the surface (Figure 1).
The amount that light bends depends on how closely packed the particles are in a material. This is called optical density and is measured using a value called the refractive index (n).
Water has a higher optical density than air, so it has a higher refractive index. When a light ray travels from air into water, it slows down and bends towards the normal. This bent ray is called the refracted ray (Figure 2), and its angle with the normal is the angle of refraction, r
(less dense material) Incident ray b
dense material)
Parallel-sided glass slab
(more dense material)
(less dense material) b Normal N aIncident ray O r i
Figure 1 Water refracts light and distorts the image.
Figure 2 (A) Light entering a less optically dense medium bends away from the normal. (B) Light
B A
Remember from Lesson 7.4 Light reflects off a mirror (page 278) that the angle of incidence (i ) is the angle between the incident ray and the normal.
When a light ray travels from water into air, it speeds up and bends away from the normal. This is why objects in water appear closer to the surface than they actually are (Figure 3).
In general:
• gases have a lower refractive index than liquids
• l iquids have a lower refractive index than solids
• t he lower the refractive index, the faster light travels through the medium (Table 1).
Table 1 The refractive index of some mediums
Figure 3 When you look at someone underwater from above the surface, they appear closer to the surface and larger than they actually are. This is because when the light refracts, it places the image in the wrong position.
Light bends because it changes speed when it enters a new medium. However, if light enters the new medium along the normal (at exactly 90°), it still changes speed, but does not bend.
Snell’s Law
Snell’s Law is a formula that describes the relationship between the angle of incidence, the angle of refraction and the refractive index of each medium (Figure 4). n1sin
Worked example 7.6A shows how Snell’s Law is used to determine the refractive index of an unknown medium.
Worked example 7.6A Calculating the refractive index of an unknown material
A laser beam passes from the air into an unknown transparent material. The angle of incidence in air is measured to be 40°, and the angle of refraction inside the material is 25°.
Given that the refractive index of air is approximately 1.00, use Snell’s Law to calculate the refractive index of the unknown material.
aWrite down what is known n1 = 1.00 n 2 = ? θ1 = 40° θ 2=25°
bSet up the formula n 2 = n1sin θ1 sin θ 2
cSubstitute the values into the formula to solve for n 2 n 2 = 1.00 × sin40 sin25 = 1.5
Figure 4 Snell’s Law
lens a curved piece of transparent material
converge (in relation to rays of light) to come together at a single point
focal length the distance between the centre of a lens and the focus diverge (in relation to rays of light) to move away from each other
virtual focus the point at which a virtual image appears
Lenses
A lens is a curved piece of transparent material, such as glass or plastic, that bends light rays that pass through it. There are two main types of lenses: convex and concave.
Convex lenses are thicker in the centre than at the edges. This causes parallel light rays to converge at the focal point. The focal length is the distance from the centre of the lens to this point (Figure 5).
Concave lenses are thinner in the centre than at the edges. This causes parallel light rays to diverge (spread out). These rays appear to come from a point on the same side of the lens as the light source. This point is called a virtual focus because the light rays do not actually meet there; it only appears that way when tracked backwards (Figure 6).
The placement of the object from the concave and convex lenses will determine the size, nature and position of the image formed (Table 2 and Figure 7). Remember, a real image is one that can be projected onto a screen, while a virtual image cannot (e.g. a reflection in a mirror).
Convex lens
Focus
Focus
Focal length
5
Concave lens
Focal length
Figure 6 Parallel rays diverge from a focus through concave lenses.
Lens
Convex >2 focal lengths Real Smaller Opposite side Upside down
2 focal lengths Real Same Opposite side Upside down
1–2 focal lengths Real Larger Opposite side Upright
1 focal lengthNot clearNot clear Infinity Not clear
<1 focal length Virtual Larger Same side Upright
Concave Any Virtual Smaller Same side Upright
Figure
Parallel rays converge at a focal point through convex lenses.
Table 2 The nature, size, position and orientation of images formed by convex and concave lenses
Figure 7 (A) Light rays from an object (P) that is more than 2 focal lengths away from a convex lens. (B) Light rays from an object (P) at the focal point of a convex lens. (C) No matter where an object is relative to a concave lens, the image is always virtual, upright, smaller and on the same side of the lens as the object.
Check your learning 7.6
Check your learning 7.6
Retrieve
1 S elect “towards” or “away from” to complete the following sentences.
a Light travelling from a high refractive index to a low refractive index will bend (towards/away from) the normal.
b Light travelling from a low refractive index to a high refractive index will bend (towards/away from) the normal.
2 Identify the two types of lenses and describe their shapes.
Comprehend
3 T he refractive index of water is 1.33 and that of diamond is 2.42. Create a diagram that illustrates how a light ray bends when it travels from water into diamond. Remember to use arrows to show the direction the light is moving in.
4 T he refractive index of glass is 1.52 and that of air is 1.00. Create a diagram that illustrates how a light ray bends when it travels from glass into air.
5 Describe how: a convex lenses are used b concave lenses are used.
Analyse
6 C ontrast how light moves through convex and concave lenses.
Apply
7 A l ight ray travels from air (n = 1.00) into glass (n = 1.50) at an angle of 30°. Calculate the angle of refraction using Snell’s Law.
8 E xplain how a convex lens is used in a magnifying glass.
Learning intentions and success criteria
Lesson 7.7
How the eye works
Key ideas
→ The human eye interprets light by converting it into electrical signals, which are sent to the brain to create the images we see.
→ People can use glasses, contact lenses or laser eye surgery to help focus light correctly onto the retina, especially if they are short-sighted or long-sighted.
→ Conditions such as astigmatism and cataracts affect how our eyes work.
How the eye works
cornea the clear, dome-shaped part at the front of the eye pupil the black circular opening in the centre of the eye iris the coloured part of the eye that surrounds the pupil lens a curved piece of transparent material
retina the lightsensitive layer at the back of the eye that converts light into electrical signals photoreceptors specialised cells called rods and cones that are responsible for colour vision, vision in low light conditions and motion detection
optic nerve the connection between the eye and the brain that transmits visual information short-sighted (myopia) where distance objects appear blurry as light rays converge in front of the retina
Light reflecting off an object and different parts of the eye work together to help you see (Figure 1).
1 L ight enters the clear, dome-shaped layer on the front of the eye called the cornea. The cornea bends (refracts) the light.
2 T he light enters the black circular opening called the pupil in the centre of the eye. The coloured area surrounding the pupil called the iris controls how much light enters the eye by adjusting the size of the pupil depending on light levels.
3 B ehind the pupil is the lens, a transparent and flexible convex structure. The lens changes shape to focus light onto the back of the eye.
4 T he focused light lands on the retina, a layer at the back of the eye that converts the light into electrical signals. The electrical signals are created by photoreceptors called rods and cones in the retina.
5 T he electrical signals travel through the optic nerve all the way to the brain, which processes and interprets the signal to produce the image you see.
Short-sightedness (myopia) and long-sightedness (hyperopia)
A person with normal vision has light rays that converge at a single point on the retina. Vision problems are caused when there are changes in the shape of the eye. When a person is near-sighted or short-sighted (myopia), the eyeball is too long or the cornea is too curved. This causes light rays to converge in front of the retina. Even though the lens is flexible, it cannot fully correct this error. As a result, distant objects appear blurry.
Retina
Cornea
Pupil Lens
Optic nerve
Iris
Figure 1 Pathway of light entering the eye
Glasses or contact lenses with concave lenses are used to correct this problem. They spread the light rays out so they focus properly on the retina, producing a clear image (Figure 2).
Distant objects appear blurry while close objects appear normal
In contrast, when a person is far-sighted or long-sighted (hyperopic) the eyeball is too short or the cornea is too flat. This causes light rays to converge behind the retina, making nearby objects appear blurry. The eyes can try to compensate by adjusting the shape of the lens, but this becomes harder with age. As a result, close-up vision becomes more difficult.
Convex lenses are used to correct this problem. They bend the light rays inwards so that they focus properly on the retina, producing a clear image (Figure 3).
Close objects appear blurry while distant objects appear normal
Laser eye surgery
While glasses or contact lenses are the most common way to correct myopia or hyperopia, laser eye surgery is another option. It works by reshaping the cornea so that light focuses correctly on the retina.
• For myopia, the cornea is too curved, so laser eye surgery flattens it to reduce its curvature.
• For hyperopia, the cornea is too flat, so laser eye surgery increases its curvature (steepens it). Not everyone is a suitable candidate. People with unstable vision, certain diseases, or corneas that are thin or irregular may not be eligible for laser eye surgery.
long-sighted (hyperopia) where close objects appear blurry as light rays converge behind the retina
With lens correction
Figure 2 Concave lenses help someone with myopia to see objects that are far away more clearly.
With lens correction
Figure 3 Convex lenses help someone with hyperopia to see objects that are nearby more clearly.
Astigmatism
Astigmatism occurs when there are multiple focal points on the retina because the cornea or lens is not perfectly round, leading to blurred or distorted vision at all distances (Figure 4A). Mild astigmatism may not need correction, but more severe cases can cause headaches and eye strain, which can be fixed with corrective lenses or laser eye surgery.
Cataracts
Cataracts are common in older adults because their lenses become cloudy. As a result, their vision is blurry or hazy (Figure 4B). Cataracts block light from reaching the retina, making it feel like you’re looking through a foggy window. Cataracts are effectively treated with surgery, in which surgeons remove the cloudy lens and replace it with an artificial lens.
Clouded lens
Check your learning 7.7
Check your learning 7.7
Retrieve
1 R ecall the function of the retina.
Comprehend
2 E xplain the difference between a real and virtual image.
3 Describe the path taken by light through the eye and how it allows us to see.
Analyse
DRAFT
4 C ontrast short-sightedness and long-sightedness and discuss the way each defect may be corrected.
5 C ompare the symptoms and causes of astigmatism and cataracts.
Apply
6 D iscuss how a person with cataracts can be treated.
7 A person has blurry vision when looking at distant objects. Identify the type of lens you would recommend. Justify your decision.
8 I nvestigate by researching whether looking at screens for an extended period of time can cause myopia. Multiple focal points
Figure 4 (A) Someone with astigmatism will have multiple focal points, while (B) someone with cataracts with have no focal point.
Lesson 7.8
Different wavelengths of light are different colours
Key ideas
→ Visible light can be separated (dispersed) into the colours of the visible spectrum: red, orange, yellow, green, blue and violet.
→ Each colour has a different wavelength and will refract different amounts to produce a rainbow.
→ An object appears coloured when some wavelengths are absorbed and others are reflected into our eyes.
Introduction
White light can separate into a wide range of colours and shades, but we generally consider there to be six basic colours: red, orange, yellow, green, blue and violet. This range of colours is known as the visible spectrum, and the process used to produce these colours is called dispersion
Sir Isaac Newton discovered this concept. Popular belief suggests he added a seventh colour, indigo, between blue and violet for good luck. This makes the colour sequence easy to remember using the acronym “ROY-G-BIV”.
Each colour in the visible spectrum has a different wavelength (the length of one complete wave cycle) and is refracted (bent) by a different amount when passing through mediums of different densities. This bending causes the colours to separate (Figure 1A). Rainbows are an example of dispersion, where the white sunlight is separated (dispersed) into its component colours (Figure 1B).
Primary and secondary colours of light
Three of the six basic colours are called the primary colours of light: red, green and blue. These colours can be combined (additive mixing) to produce white light.
Learning intentions and success criteria
Check the next lesson for a linked practical activity or experiment.
visible spectrum the range of colours in light wavelengths that can be seen by the human eye dispersion the separation of white light into its different colours
primary colours of light the three colours of light (red, blue and green), which can be mixed to create white light
Figure 1 (A) The refraction of white light separates it into its component colours. (B) Refraction is how we get the colours of a rainbow.
secondary colours of light the colours of light (magenta, cyan and yellow) that result from the mixing of two primary colours of light
complementary colours of light two colours that produce white light when combined filter a transparent material that allows only one colour of light to pass through transmit to allow light to pass through
When two of the primary colours are combined, they form secondary colours of light (Figure 2).
• Red + blue = magenta
• Blue + green = cyan
• G reen + red = yellow
If cyan light is mixed with red light, the result is white. When only two colours are needed to make white light, they are called complementary colours of light
Note: The colour-mixing rules only apply to light. If you are an art student, you will need to think differently when mixing colours of paint!
Colour of opaque objects
Why do objects appear to be coloured? When white light (or sunlight) shines on an opaque object, some colours (wavelengths of light) are reflected, while others are absorbed (soaked up or subtracted from the white light) (Figure 3). The colour we see depends on the mix of colours that are reflected into our eyes. In most cases, it is easier to consider white light as just made up of red, green and blue light.
If certain colours are absorbed and others reflected, the object appears to be the colour of the light it reflects. This rule also applies when objects are illuminated by coloured light. For example:
• A red top appears red because it reflects red light and absorbs the other colours.
• G rass appears green because it reflects green light and absorbs red and blue light.
Colour of transparent objects
Yellow 2. Magenta 3. Cyan 23
Figure 2 Where the red, green and blue lights overlap, white light is produced. The secondary colours are formed by the additive mixing of two primary colours.
DRAFT
All colours are absorbed. No light is reflected.
Figure 3 (A) Grass reflects green light and so looks green. (B) Black surfaces absorb all colours and so they look black. No colours are reflected.
Transparent objects, such as cellophane and the filters in a Hodson light box kit, behave differently. They transmit (allow to pass through) some colours and absorb others. The colour we see is the colour of the light that passes through the transparent material. For example:
• A red filter appears red because it transmits red light and absorbs blue and green light.
• A blue filter appears blue because it transmits blue light and absorbs red and green light (Figure 4).
4 A filter that transmits blue light and absorbs red and green light will appear blue.
Red light
Blue glass
Green light
Blue light
Figure
B G White light Green light is reflected.
Green grass Blue and red light is absorbed. R
Black surface
B G White light R
Check your learning 7.8
Check your learning 7.8
Retrieve
1 Describe what the visible spectrum is.
2 Identify the colour that is produced when magenta light and green light are mixed.
3 Identify what colour a red object appears as under a red light.
Comprehend
4 I f white light is a mixture of all the primary colours of light, explain what black is.
5 Describe the difference in the way opaque and transparent objects interact with light.
Analyse
6 C ontrast how light moves when hitting a filter and when hitting an opaque object.
7 C ontrast the primary and secondary colours of light.
Lesson 7.9
8 I nterpret what happens when white light passes through a red filter and then hits a green object.
9 C ompare the appearance of a blue object under white light, red light and blue light.
Apply
10 Describe what you would see if you looked at a white light through a yellow filter. Justify your answer (by describing what happens to each of the primary colours of white light when they hit a yellow filter).
11 Describe the colour that a green surface will appear in red light. Justify your answer by explaining what happens when red light hits a green surface.
Experiment: What colour is it?
Aim
To investigate the addition of coloured light and explore the behaviour of coloured filters
DRAFT
Materials
• Hodson light box kit
• Power supply
• Sheet of white paper
Method
1 Connect the light box to a power supply and place it on the sheet of paper.
2 Place the three primary filters (red, green and blue) in each of the three separate slotted sections in the light box. Adjust the mirror flaps so that the colours can overlap on the paper. Change the combination of filters, and copy and complete Table 1.
Table 1 Results for primary colour filters
Colours of filtersColour produced
Red + green + blue
Red + blue
Green + blue
Red + green
3 C hange the combination of filters, and copy and complete Table 2.
Table 2 Results for a combination of primary and secondary colour filters
Colours of filtersColour produced
Yellow (side slot) + blue (front slot)
Magenta (side slot) + green (front slot)
Cyan (side slot) + red (front slot)
4 Switch off the light box and remove the filters. Select a red, green, blue and yellow opaque surface from the light box kit. Hold each of the coloured surfaces against the back of each primary filter. Record in Table 3 the colour that each surface appears.
Table 3 Results when viewing the colour of surfaces through primary colour filters
Surface colour
Colour surface appears when viewed through a: Red filterGreen filterBlue filter Green
DRAFT
Learning intentions and success criteria
Lesson 7.10
Discussion
1 Identify the combinations of colours that produce white light.
2 Describe any patterns you observed in each of the tables. Explain the patterns you observed.
3 Identify one possible source of error in the experiment.
4 Describe the difficulties you had, and how you overcame them.
Conclusion
Describe what happens when coloured lights are added to each other.
The electromagnetic spectrum has many uses
Key ideas
→ Total internal reflection occurs when a light ray passes into a less dense medium at a particularly large angle.
→ Optic fibres use total internal reflection to pass data in the form of light pulses.
→ Other forms of the electromagnetic spectrum, such as microwaves, are used for communication and for cooking food.
or experiment.
Total internal reflection
Many optical instruments, such as cameras, microscopes and some telescopes, use lenses, but several also use prisms to reflect light. A prism is a block of glass that can bend and reflect light in specific ways. When light passes from a denser medium to a less dense medium (for example, from glass to air), it is refracted away from the normal. As the angle of incidence increases, the refracted ray bends more and more until it travels at 90° to the normal, skimming along the boundary between the two media. This angle is called the critical angle (symbol i c ).
By increasing the angle of incidence to be greater than the critical angle, the light is reflected into the original, more dense medium (higher refractive index), as opposed to being refracted into the less dense medium (lower refractive index). This is known as total internal reflection (Figure 1).
critical angle the angle of light that causes the reflected ray to move along the edge between two materials total internal reflection the complete reflection of a light ray when it passes from a more dense to a less dense material at a large angle; the ray is reflected back into the dense medium
Less dense material
More dense material
RefractionRefraction
Total internal reflection
Using total internal reflection
Optic fibres have revolutionised communication. Instead of using copper wires to carry electrical signals, we now use bundles of optic fibres to carry light signals for landline telephone calls, the internet and the NBN (National Broadband Network) (Figure 2).
An optic fibre is a very thin fibre of glass or plastic that carries light, which reflects off the internal surface using total internal reflection (Figure 3). By sending information as controlled pulses of light, a single fibre, less than a millimetre wide, can carry thousands of phone calls and millions of bits of data.
DRAFT
Total internal reflection
Figure 1 (A) Rays a and b are refracted because the angle of incidence is less than the critical angle. Ray c occurs when the critical angle is reached. Ray d is reflected when the angle of incidence is greater than the critical angle. (B) Total internal reflection
Advantages of optic fibres over copper wires include:
• less signal loss
• more capacity to send data
• safe around high voltages
optic fibre a thin fibre of glass or plastic that carries information/data in the form of light
A B
Figure 2 Optic fibres are used to carry digital light signals and have various applications.
• no fire risk
• i mmune to electromagnetic interference
• reduced need for booster stations because data can travel long distances.
Microwaves
Microwaves are one small part of the electromagnetic spectrum, with wavelengths between 1 millimetre and 1 metre. Microwaves have many uses, including:
• communication (mobile phones)
• cooking
• g lobal positioning systems (GPS)
• r adar.
Light in
Glass cladding
Glass core
Light out
DRAFT
Microwaves can be focused into narrower beams than radio waves, making them ideal for point-to-point communication, including between Earth and the International Space Station (Figure 4).
Microwaves pass through the atmosphere
Radio waves reflected from a charged layer of the upper atmosphere
Signal received even though transmitter and receiver are not in the line of sight
1 Describe when and how total internal reflection
2 Describe why optic fibres are better for telecommunications than copper wire.
3 E xplain why the amount of water in the food is important when cooking in a microwave.
Figure 3 Light zigzags along inside an optic fibre at the boundary of the core and the cladding.
Atmosphere
Figure 4 Electromagnetic waves with different wavelengths behave differently in Earth’s atmosphere.
Analyse
4 C ontrast total internal reflection and the reflection from a plane mirror.
5 E xplain why total internal reflection only occurs when light travels from a more dense to a less dense medium.
Apply
6 D iscuss why total internal reflection cannot occur for light passing from a less dense material into a denser material.
7 I nvestigate one other use for other forms of electromagnetic waves.
Lesson 7.11
Experiment: What is the wavelength of a microwave?
Caution
Some students might have egg allergies.
Context
A microwave oven uses electromagnetic waves to heat food (Figure 1). These waves move through the cooking area in a set fashion. All microwave ovens have turntables to rotate food so that it cooks evenly. This is because of the wavelike motion of the energy.
Without the turntable, the energy is focused on fixed parts of the oven. You can use this to determine the wavelength of the microwaves in your microwave oven (Figure 2).
DRAFT
Aim
To determine the wavelength of a microwave
Materials
• M icrowave oven with the turntable removed
• L arge flat plate at least 20 cm in diameter (safe for use in a microwave) or a piece of black cardboard approximately the same size
• O ven mitts
• E gg white
• Ruler
Figure 1 A microwave oven uses electromagnetic waves to heat food.
Figure 2 A microwave oven with the rotating platter removed, and the drive mechanism removed
Method
1 C rack an egg and separate the egg white from the egg yolk.
2 Spread the egg white evenly over the plate or black cardboard.
3 Place the plate or cardboard in the oven and turn it on for 15 to 30 seconds (depending on the power of the microwave). The egg should start cooking in stripes or patches.
4 Remove the plate or cardboard from the microwave and identify the centre of the cooked stripes or patches. Measure the distance between two of the cooked patches (Figure 3).
5 Repeat this experiment several times and determine the average distance between the cooked egg white patches.
Results
1 Record all your observations in a table.
2 Multiply the average distance between the cooked egg white by 2 to determine the length of a full wavelength.
Discussion
1 Identify the wavelength of the microwaves in your microwave oven.
2 Describe any difficulties you had when determining the centre of the cooked portion of egg. Calculate the error margin of your calculation (± the width of the cooked egg bands).
Lesson 7.12
DRAFT
3 E xplain why you needed to repeat your experiment several times.
Conclusion
Explain what you know about the wavelength of microwaves.
Review: Particles and waves
Summary
Lesson 7.1 Vibrating particles pass on sound
• Sound is caused by the vibration of particles moving in a longitudinal wave.
• O ne wavelength is the distance between one compression of air particles and the next, and the time taken for a wave to complete a cycle is called the period.
Figure 3 Use the cooked portions of the egg white to measure the distance between “hot spots” in the microwave oven.
• T he distance an air particle moves is called the amplitude.
• T he number of waves passing a point each second is the frequency of the wave.
• A n object's resonance is caused by vibrations that match the frequency of another object.
• Resonance is the natural tendency of objects to vibrate more vigorously at some frequencies than others.
• We are able to hear things because the ear has an auditory nerve that turns vibrations in the air into a signal that the brain interprets.
• T here are different types of hearing loss depending on which part of the ear is not functioning properly, and they include conductive and sensorineural hearing loss.
Lesson 7.2 Sound can travel at different speeds
• T he speed of sound through air at sea level and at 20°C is approximately 340 m/s.
• T he temperature and material through which sound travels will affect the speed of sound.
• At higher temperatures, particles are compressed more easily because of their higher kinetic energy.
• T he more closely packed the particles, the faster the sound wave travels.
• Sound can be reflected, and this property of sound is used in sonar, echolocation and medical imaging.
Lesson 7.3 Light
• L ight travels as an electromagnetic wave with a transverse motion.
• E lectromagnetic waves in a vacuum travel at the same speed.
• L ight also behaves like a particle called a photon.
Lesson 7.4 Light reflects off a mirror
• L ight can travel through transparent objects and is blocked by opaque objects.
• Translucent objects allow some light through.
• W hen light is reflected off a mirror, the angle of incidence is equal to the angle of reflection (Law of Reflection).
• T he image in a mirror is called a virtual image.
Lesson 7.6 The refraction of light
• Refraction is when light bends as it enters or leaves a medium.
• L ight entering a more optically dense medium bends towards the normal.
• L ight entering a less optically dense medium bends away from the normal.
• Snell’s Law determines the refractive index of an unknown material.
• L enses allow light to diverge or converge.
Lesson 7.7 How the eye works
• T he human eye interprets light by converting it into electrical signals, which are sent to the brain to create the images we see.
• People can use glasses, contact lenses or laser eye surgery to help focus light correctly onto the retina, especially if they are short-sighted or long-sighted.
• Conditions such as astigmatism and cataracts affect how our eyes work.
Lesson 7.8 Different wavelengths of light are different colours
• Visible light can be separated (dispersed) into the colours of the visible spectrum: red, orange, yellow, green, blue and violet.
• E ach colour has a different wavelength and will refract different amounts to produce a rainbow.
• A n object appears coloured when some wavelengths are absorbed and others are reflected into our eyes.
Lesson 7.10 The electromagnetic spectrum has many uses
• Total internal reflection occurs when a light ray passes into a less dense medium at a particularly large angle.
• O ptic fibres use total internal reflection to pass data in the form of light pulses.
• O ther forms of the electromagnetic spectrum, such as microwaves, are used for communication and for cooking food.
Review questions 7.12
Review questions
Retrieve
1 Identify which of the following terms is used to describe sound waves.
A Transverse waves
B E lectromagnetic waves
C M icrowaves
D L ongitudinal waves
2 Identify which of the following is correct.
A Sound waves travel faster than light waves.
B Sound travels faster in air than in water.
C L ight travels faster than sound.
D Sound can travel through space.
3 Define the term “frequency” of sound. Identify its unit.
4 Identify the missing words and complete the following paragraph. The first letter of each missing word is given.
Sound is created by v_______. The v_______ create c_______ and r_______ due to the movement of the particles as the sound w_______ passes through. The w_______ travels through the substance and is known as a l_______ wave. The greater the vibration, the higher the v_______ of the sound, which means it sounds l_______. Sound waves must have a m_______ to pass through.
Comprehend
5 E xplain why astronauts could shout at each other with their helmets touching if the radio communication broke down on the Moon.
6 D raw a flow chart to show how sound waves entering the outer ear reach the auditory nerve to translate it into a sound.
7 Butchers sometimes use red lights to illuminate the meat in their shop windows. Explain why they might choose this colour.
13 Describe the appearance of the Australian flag when viewed in: a blue light
b red light
c g reen light.
Analyse
14 C ompare transverse waves and longitudinal waves.
DRAFT
8 Explain why sound travels faster in solids than in air.
9 Describe the difference between the primary colours of light and the primary colours of paint.
10 E xplain how pitch and frequency of sound are related.
11 Describe the conditions that can slow the speed of light.
12 Describe how light moves in an optic fibre.
15 C ompare the reflection of light and the refraction of light.
16 C ompare short-sightedness and long-sightedness. Describe what happens with each eye vision condition and explain the use of appropriate lenses to correct it.
Apply
17 A student claimed that black is not a colour. Evaluate their claim (by explaining how an object can appear black, defining what a colour of light is, and deciding if the student is correct).
18 Aboriginal and Torres Strait Islander peoples use the didjeridu for many important ceremonies. Long didjeridus produce sounds that are lower in pitch and frequency than short didjeridus (Figure 1). Describe what this information tells you about the sound wave that is produced. (HINT: Consider the length of the sound waves produced by each didjeridu.)
Figure 1 Didjeridus of different lengths
Critical and creative thinking
19 Table 1 shows the speed of sound at different temperatures.
a Using graph paper, create a graph of the speed of sound (vertical axis) at various air temperatures (horizontal axis).
b Describe what happens to the speed of sound as the temperature increases.
c Use your graph to identify the speed of sound at 5°C.
d Use your graph to identify the temperature of the air if the speed of sound is 351 m/s.
Supersonic planes
• Identify what “supersonic sound” means.
• C ontrast a supersonic jet and a normal jet aircraft.
• Describe one of the problems with supersonic planes.
• Describe why the Concorde was removed from air travel service.
20 A stronauts in space can still see each other even if they cannot hear each other.
a Use this information to compare how light and sound travel.
b Determine what this tells us about the ability of light energy to travel through outer space.
21 I nvestigate the differences and similarities between audible sound, ultrasound and infrasound. Display your answer using a Venn diagram.
Research
22 C hoose one of the following topics for a research project. A few guiding questions have been provided, but you should add more questions that you wish to investigate. Present your report in a format of your own choosing, but one component of your report must include a demonstration of sound (for example, if you make an instrument, it needs to be played). In a multimedia presentation, sound must be part of the presentation. If you interview someone as part of your research, you must present a taped recording of your interview along with your report.
DRAFT
Night vision goggles
Night vision goggles are used by soldiers to see at night.
• Describe how night vision goggles work.
• Identify the limitations of night vision goggles. Will they work in a totally dark environment? Are there any disadvantages for the soldiers operating them?
Table 1 The speed of sound at different temperatures
Figure 2 The Concorde, which entered service in 1976, was a supersonic passenger plane able to fly from London to New York in under three hours. This flight typically took eight hours on a regular passenger plane.
Figure 3 View of deer and forest through night vision goggles
[STEAM project 1] How can we use sustainable farming practices so that no one goes hungry in the future?
Your task
The United Nations ranks food shortages and hunger among the most serious issues affecting humankind. It predicts that more than 840 million people will be hungry by 2030. Even in a highincome country such as Australia, 5 per cent of the population are unable to access enough nutritious food. The experience of having inadequate access to food or having an inadequate supply of food is known as food insecurity. Food insecurity is linked to poor general health, higher rates of some cancers and higher mortality.
Rapid climate change is increasing threats to Australia’s and the world’s food security. Changes in the amount of rainfall, longer droughts and an increase in the number of extreme weather events are expected to disrupt the amount and quality of food that Australia can produce. A hotter climate is expected to cause stress in livestock animals, such as chickens, sheep and cattle, and to increase the amount of water needed for crop irrigation.
Sustainable farming
DRAFT
Sustainable farming practices use methods that balance the needs of all members of the community. This means that new and old technologies are used to make sure that food production is:
• economically viable – if farmers cannot make enough money to survive, then the farming practice is not sustainable
• socially supportive – if the lifestyle of the farming community is not supported, then people will not want to live in the area
Increase the growing capacity (productivity) of a one hectare (100 m × 100 m) plot of land by designing a vertical garden that won’t damage the local environment.
• ecologically sound – if the local environment is not supported, then the land will be unable to support food production.
Sustainable farming also works to maintain the diversity of the local wildlife.
Figure 2 Drought impacts Australia’s production of important crops, such as wheat.
Figure 1 Vertical farming allows people to grow more food in a smaller space.
HUMANITIES
In Geography this year, you will learn about food security around the world and food production in Australia. You will investigate the factors that influence crop yield (such as temperature and rainfall) and how food production can alter a biome. In Economics and Business, you will look at exports, such as agricultural resources, that form a large part of Australia’s trade economy.
To complete this task successfully, you will need to investigate the environmental constraints on agricultural production in Australia, such as climate and distribution of water resources. You will also need to understand the extent to which agricultural innovations have overcome these constraints.
DRAFT
You will find more information on this in Module 3 “Food security”, Module 2 “Biomes” and Module 10 “Understanding the economy” of Oxford Humanities and Social Sciences 9 Western Australian Curriculum
MATHS
In Maths this year, you will build on your knowledge of measurement and geometry to determine areas and volumes of more complicated shapes. You will study right-angled triangles using Pythagoras’ theorem and trigonometry. You will also extend your skills in collecting, representing and investigating data.
To complete this task successfully, you will need to perform calculations involving angles, lengths and areas of two-dimensional and three-dimensional shapes. You will need to apply your understanding of scale factors to build a prototype of your designed product. To consider the situation at local, national and international scales, you will need skills in dealing with ratios and proportions. You may also find it helpful to use scientific notation for very large or very small numbers.
SCIENCE
In Science this year, you will learn about the carbon cycle and the ways human activity can disrupt it. You will also consider the consequences of disruption, including the enhanced greenhouse effect. You will also learn about asexual reproduction and investigate vegetative propagation.
Sustainable farming uses technology to increase the production of fresh, nutritious food while minimising the impact on the local environment.
To complete this task successfully, you will need to understand the factors required to keep a system, such as a vertical garden, alive. You may need to consider how these factors can be monitored and controlled automatically. You will also need to be familiar with the scientific method and understand how to conduct a fair test.
You will find more information on this in Module 2 “Adaptations” and Module 6 “The carbon cycle” of Oxford Science 9 Western Australian Curriculum.
[STEAM project 1] The design cycle
To successfully complete this task, you will need to complete each of the phases of the design cycle.
discover
define communicate test ideate build
Discover
When designing solutions to a problem, you need to know who you are helping and what they need. The people you are helping, those who will use your design, are called your end-users.
Consider the following questions to help you empathise with your end-users:
• W ho am I designing for?
• W hat problems are they facing? Why are they facing them?
• W hat do they need? What do they not need?
• W hat does it feel like to face these problems?
To answer these questions, you may need to investigate using different resources or conduct interviews or surveys.
Define
Before you start to design your vertical garden, you need to define the criteria that you will use to test the success of your vertical garden in achieving your goal.
Define your version of the problem
Rewrite the problem so that you describe the group you are helping, the problem they are experiencing and why it is important. Use the following phrase as a guide:
“How can we help (the group) to solve (the problem) so that (the reason)?”
Determine the criteria
1 W hat is the total area of the 100 m × 100 m plot of land? (Remember to use the correct units.)
2 I f the plants are planted 25 cm apart in a 100 m row, and the rows are placed 1 m apart, how many plants could be planted in the plot of land?
Hint: Draw the plot of land to make sure you reach maximum capacity.
3 W hat criteria will you use to measure the success of your solution or design? How will you measure how much the end-users have been helped?
Ideate
Once you know who you’re designing for, and you know what the criteria are, it’s time to get creative!
As a group, brainstorm ways the problem can be solved. Remember that there are no bad ideas at this stage. One silly thought could lead to a genius innovation!
Once you have many possible solutions, it is time to sort them by possibility. Select three to five ideas that are possible. Research whether these ideas have already been produced by someone else. If they are already on the market, can you make a better version?
Build
Draw your top two vertical garden designs. Label each part of the designs. Include the materials that will be used for their construction.
Include in the designs:
a the total surface area available for plant growth
b a descr iption of how food production will be increased
c a descr iption of how the design (inputs and waste) will impact the local ecosystem
d a descr iption of how the workers will access all areas of the design to tend the plants
e at least one advantage and disadvantage of each design.
Select one of the designs to take to the building and testing stage.
Build the prototype
You will need to build at least three versions of your vertical garden design prototype. The first prototype garden will be tested for effectiveness. The second prototype will be used to survey the group you are helping. The third prototype will be used for the presentation. The prototype may be full size, or it may be a scale model (10 cm represents 1 m). Use the following questions as a guideline for your prototype:
• W hat materials will you use?
• W hat material will you use to represent the plants?
• How will you represent the height, width and angle of the finished prototype?
Test
Prototype 1
Use the scientific method to design an experiment that will test the effectiveness and strength of your first vertical garden prototype. You will test the prototype more than once to compare results, so you will need to control your variables between tests. What criteria will you use to determine the success of your prototype? Conduct your tests and record your results.
Prototype 2
If your prototype will be used to help market gardeners, then you will need to generate a survey to test whether the prototype is appropriate for their use. (How would they use it? Would they consider buying it?)
If your prototype will be used to help another group, or native plants and animals, you will need to consider how you could test the impact it will have. (Will the prototype affect normal behaviours? How will the prototype affect the soil or waterways?)
Prototype 3
DRAFT
Use the information you have obtained from testing the first two versions to adapt your last prototype to be more effective and usable for the group you are helping. You may want to use the first two prototypes to demonstrate how the design has been improved.
Communicate
Present your vertical garden design to the class as though you are trying to get your peers to invest in it. Describe the criteria and testing used to measure the effectiveness of your vertical garden design.
In your presentation, you will need to:
• explain why we need to be more efficient with food production
• describe the key features of your design and how they improve or solve the problem of food shortages
• show a labelled, to-scale diagram of your prototype
• describe how the ecosystem will be affected by the installation of the prototype
• explain the relevant scientific principles that support your designed solution (e.g. water cycle, photosynthesis, nitrogen/carbon cycle)
• quantify the increase in food production that your design allows; present calculations to justify your claim
• present a calculation for the estimated cost of producing a full-size model of your design
• explain the implications of your design, at a state or national level, by comparing the benefits and costs.
A disorder or disease is a condition that affects the normal functioning of the body. Different disorders and diseases can affect many parts of the body. They can be caused by infectious agents such as bacteria or viruses that spread from person to person. Some disorders or diseases are inherited. Environmental factors (such as pollution or diet) can also have an impact on the development of disorders or diseases.
Heart disease, a non-infectious disease, is the leading cause of death globally. Mental health disorders, such as depression, bipolar disorder and dementia, also affect many people around the world.
Disorders and disease affect both high-income and low-income countries, but there are large differences in the ability of different healthcare systems to provide adequate care for people. The need for low-cost health care has led many researchers to investigate how technology can be used to help people live healthier lives.
[STEAM project 2] How can we harness technology so that we can live healthier lives?
Prevention of disorders and disease
There are many disorders and diseases that can be prevented through simple, low-cost interventions. Below are a few examples.
• Wearing a helmet or a seat belt has been shown to decrease the risk of brain injury from a road accident. In Vietnam, when wearing a helmet was made mandatory for motorcycle riders, it resulted in a 16 per cent decrease in head injuries.
• T he use of mosquito nets can help to prevent malaria, a disease that can lead to life-long neurological impairment, such as epilepsy in children if they have a severe infection.
Your task
Develop a strategy to help prevent a disorder or disease within a chosen at-risk
prevent the spread of infectious disease.
• P roviding vaccinations for viruses such as polio and meningitis can also prevent neurological conditions.
• P romoting a healthy lifestyle and educating the population about the importance of diet can reduce the prevalence of stroke. In Japan,
Figure 1 During the 1918 flu pandemic (sometimes called the Spanish flu), an estimated 500 million people, a third of the world’s population, were infected with the virus.
group.
Figure 2 Healthcare workers wear personal protective equipment (PPE) to
HUMANITIES
In Geography, you will study how people are interconnected through travel, technology and trade. These connections affect where and how people access the services they need. In History, you will examine the experiences of different groups during the Industrial Revolution and the reforms made to improve living standards.
To complete this task successfully, you will need to research the demographics of your local area and the location and accessibility of health services. You should also consider the economic performance of your area to determine what type of preventative strategy would be most successful for your at-risk group.
You will find more information on this in Module 3 “Food security”, Module 2 “Biomes” and Module 10 “Understanding the economy” of Oxford Humanities and Social Sciences 9 Western Australian Curriculum.
DRAFT
MATHS
In Maths this year, you will extend your skills in representing and interpreting data. You will consider media reports that use statistics and collect secondary data to investigate social issues. You will relate real-world data to probabilities of events, and compare data sets using summary statistics and different graphical displays. You will evaluate and represent data, both with and without digital technology.
To complete this task successfully, you will need to find data to quantify the problem, work out how much your strategy will cost and calculate a quantitative, evidence-based estimate of the possible benefits of your strategy. You will need skills in dealing with ratios, proportions and percentages to consider the situation at local, national and international scales.
SCIENCE
In Science this year, you will learn about how the body coordinates and regulates its internal systems so that it can respond to changes. When things change in the environment (such as the emergence of a diseasecausing agent) or a part of the body fails, the normal functioning of the body is interrupted. The body needs to respond and attempt to return to a normal homeostatic state before permanent damage is caused.
To complete this task successfully, you will need to identify how the body’s systems work together to maintain a functioning body. You should consider the type of disorder or disease that you will be fighting and how it may cause changes in the body’s normal function and response mechanisms.
You will find more information on this in Module 3 “Control and regulation” of Oxford Science 9 Western Australian Curriculum campaigns and treatment for high blood pressure have reduced the rate of strokes by 70 per cent.
• Personal protective equipment (PPE) is used to protect people from catching infectious diseases, such as Covid-19. Oxford University Press
[STEAM project 2] The design cycle
To successfully complete this task, you will need to complete each of the phases of the design cycle.
discover define communicate test
ideate
build
Discover
When designing solutions to a problem, you need to know who you are helping and what they need. The people you are helping, who will use your design, are called your end-users.
Consider the following questions to help you empathise with your end-users:
• W ho am I designing for? Is it the people directly affected by the disorder or disease, or do their families and carers need support too?
• W hat problems are they facing? Why are they facing them?
• W hat do they need? What do they not need?
• W hat does it feel like to face these problems? What words would you use to describe these feelings?
To answer these questions, you may need to investigate using different resources or conduct interviews or surveys.
Define
Before you start to design your solution to the problem, you need to define the parameters you are working towards.
Define your version of the problem
Rewrite the problem so that you describe the group you are helping, the problem they are experiencing and why it is important. Use the following phrase as a guide.
“How can we help (the group) to solve (the problem) so that (the reason)?”
Determine the criteria
1 Describe the type of life that the people you are helping lived before their lives were affected by the disorder or disease.
2 Describe how the people affected by the disease have needed to change their lives to cope with the effects of the disorder or disease.
3 Describe how you will know that you have made their lives better as a result of your prototype strategy.
Ideate
Once you know who you’re designing for, and you know what the criteria are, it’s time to get creative!
Outline the criteria or requirements your design must fulfil (i.e. usability, accessibility, cost).
Brainstorm at least one idea per person that fulfils the criteria.
Remember that there are no bad ideas at this stage. One silly thought could lead to a genius innovation!
Build
Each group member should draw an individually designed solution. Label each part of the design. Include the materials that will be used for its construction. Include in the individual designs:
a a detailed diag ram of the design
b a descr iption of why it is needed by the individual or group
c a descr iption of any similar designs that are already available to buy
d an outline of why your idea or design is better than others that can be purchased. Present your design to your group.
Build the prototype
Choose one design and build two or three prototypes. Use the following questions as a guideline for your prototype.
• W hat materials or technology will you need to build or represent your prototype design?
• W hat skills will you need to construct your prototype design?
• How will you make sure your prototype design is able to be used by the people who need it?
• How will you describe the way the prototype design will work?
Test
Prototype 1
Use the scientific method to design an experiment that will test the effectiveness and strength of your first prototype. You will test the prototype more than once to compare results, so you will need to control your variables between tests.
Prototype 2
If your prototype will be used to help individuals with the disorder or disease, then you will need to generate a survey to test whether the prototype is appropriate for their use. (How would they use it? Would it make their life easier or harder? Would they consider buying it? How much would they be willing to pay to access the design?)
Prototype 3
Your last prototype should be adapted using the information gathered from testing the first two versions to make it more effective and usable for the group you are helping. You may want to use the first two prototypes as a demonstration of how the design has been improved over time.
DRAFT
What criteria will you use to determine the success of your prototype?
Conduct your tests and record your results in an appropriate table.
Communicate
Present your design to the class as though you are trying to get your peers to invest in your design. In your presentation, you will need to:
• outline the relevant disorder or disease and how it affects individuals, as well as society as a whole
• c reate a working model or a detailed series of diagrams, with a description of how it will be used by an individual or group
• explain how you changed your design as a result of testing or feedback
• describe how the design will improve the life of an individual or group
• describe how many people need or will use the design
• describe how individuals will be able to access the design (will they need to purchase it or will it be publicly funded?)
• describe how the design will improve an individual’s ability to contribute to society as a whole.
Student booklet
This helpful booklet will guide you step-by-step through the project.
What is the design cycle?
This video will help you to better understand each phase of the design cycle.
How to manage a project
This “how-to” video will help you to manage your time throughout the design cycle.
How to pitch your idea
This “how-to” video will help you with the “Communicate” phase of your project.
Glossary
Aabiotic factors
non-living factors that influence an ecosystem, such as wind, water, salinity and temperature accuracy
how carefully, correctly and consistently data have been measured or processed; in science, how close a measured value is to the true value actinides
subset of metallic elements found in period 7 of the periodic table aeration
process of circulating or mixing air through water
aerobic applies to respiration that occurs with oxygen and releases more energy, and usually more slowly, than anaerobic respiration
aerobic cellular respiration
a chemical reaction between glucose and oxygen to produce carbon dioxide, water and energy aim
the purpose of an experiment alkali metal
an element in group 1 of the periodic table
alkaline earth metals
elements with similar properties found in group 2 of the periodic table
alpha particle
a radioactive particle containing two protons and two neutrons; can be stopped by a piece of paper amplitude
the distance a particle in a wave moves from its position of rest amygdala
angle of reflection
the angle between a reflected ray and the normal (a line drawn at right angles to a reflective surface) angle of refraction
the angle between a refracted ray and the normal (a line drawn at right angles to a refractive surface) anion
a negatively charged ion formed when an atom gains electrons annual
(in relation to plants) a type of plant that only lives for one growing season before dying off atmosphere
the layer of gases surrounding Earth atomic mass
the total mass of an atom
atomic number
the number of protons in an atom
atomic radius
the distance from the nucleus of an atom to its outermost electron
atomic theory
the theory that all matter is made up of atoms
autonomic nervous system
the part of the nervous system that controls involuntary actions such as heartbeat, breathing and digestion axon
the part of a neuron (nerve cell) that carries an electrical message away from the cell body to the synapse
B
belt transects
biosphere
a layer around Earth’s surface that supports life; consists of the atmosphere, hydrosphere and lithosphere
biotic factors
living factors that influence an ecosystem such as animals, plants and bacteria and the relationships between them
blackwater
DRAFT
a part of the brain responsible for encoding the emotional part of a memory
anaerobic applies to respiration that occurs without oxygen and releases less energy, and usually more quickly, than aerobic respiration
angle of incidence
the angle between an incident ray and the normal (a line drawn at right angles to a reflective surface)
a rectangular area along a transect line where quadrats are placed at regular intervals to collect samples
beta particle
a radioactive particle (high-speed electron or positron) with little mass; can be stopped by aluminium or tin foil bias
discrimination against ideas, against people or in the collection and interpretation of information biodiversity
the variety of life; the different plants, animals and mircroorganisms and the ecosystems they live in
wastewater from toilets, kitchens and dishwashers blooms
the rapid increase in the population of algae; can cause a body of water to change colour
Ccapture–recapture
a method used to estimate an animal population’s size where it is impractical to count every individual carbon dating
a method of estimating the age of organic material, by comparing the amount of carbon-14 in the material with the amount in the atmosphere, knowing the rate at which carbon-14 decays over time
carbon sink
any feature of the environment that absorbs and/or stores carbon carbon tax
a tax levied on the carbon content of fuels used by businesses or homes carbon trading scheme
the process of allocating a set limit of carbon credits to businesses, who can then trade the credits catchment area
the area of land, including hills and mountains, woodlands and buildings, that water drains from before flowing into streams, rivers and lakes categorical data
information that can be divided into groups or categories cation
a positively charged ion that results from an atom losing electrons causation when the independent variable is responsible for the change in the dependent variable
cell body
the main part of a cell that contains the nucleus and genetic material
cellular respiration
chemical reaction that transfers energy to cells
census
a complete count of a population (in a given state or location)
central nervous system
the brain and spinal cord cerebellum
a small lobe at the lower rear of the brain responsible for fine motor movement, balance and coordination cerebral cortex
the outer layer of the brain that is responsible for conscious thought cerebrum
the outer layer of the brain which consists of the left and right hemisphere chalcogens
elements found in group 16 of the periodic table that are commonly found in ores
climate
the weather conditions at a particular place, averaged over a long period of time, based on the collection and analysis of large amounts of data
climate change
periodic change in Earth’s climate climate change mitigation
efforts that aim to reduce or prevent greenhouse gas emissions coagulation
process of becoming viscous or thickened coefficient
the number in front of the chemical formula combustion reaction
a reaction between a fuel and oxygen that produces heat, carbon dioxide and water commensalism
a type of relationship between two organisms of different species in which one organism benefits and the other is not affected community
compression
part of a sound wave where air particles are forced close together compression wave
(also known as longitudinal wave)
a type of (sound) wave where the particles move in the direction of travel of the wave concave
refers to a lens or mirror that is thinner in the centre than at the ends condensation
the process where water vapour becomes liquid water conduction
the transfer of thermal energy from hot objects to cooler objects through direct contact with no movement of material continuous data
information that can be any value, including decimals and fractions that are measured
controlled variables
variables that remain unchanged during an experiment convection
the transfer of thermal energy by the movement of molecules in air or liquid from one place to another converge (in relation to rays of light) to come together at a single point convex
refers to a lens or mirror that is thicker in the centre than at the ends Coriolis effect
the influence of Earth’s rotation on the direction of movement of air or water cornea
the clear, dome-shaped part at the front of the eye correlation
the positive, negative or zero relationship between two variables corrosive
cryosphere
the frozen water in the hydrosphere
cultural burning
the practice of burning vegetation used by Traditional Custodians of Country to enhance the health of Country; informed by deep knowledge of and relationship to Country
Ddendrite
DRAFT
a substance that can damage or destroy other materials covalent bond
different populations living in the same location at the same time competition
contest between organisms that require or seek similar resources such as shelter and food
complementary colours of light two colours that produce white light when combined
a chemical bond or an attraction between atoms, where atoms share electrons covalent compound
a substance made up of two or more non-metal atoms by sharing valence electrons
critical angle
the angle of light that causes the reflected ray to move along the edge between two materials
the part of a neuron (nerve cell) that receives a message and sends it to the cell body
dependent variable
a variable in an experiment that may change as a result of changes to the independent variable desalination
process of removing salts and other minerals from water to make it suitable for human consumption, irrigation or industrial uses
discrete data
information that can only take on specific and distinct values, such as whole numbers
discussion
an interpretation of the findings, including improvements to the investigation and suggestions for further investigation
disinfection
a process that removes microbes or potentially harmful microorganisms dispersion
the separation of white light into its different colours
diverge
(in relation to rays of light) to move away from each other ductile
a property of a substance which means it can be stretched, pulled or drawn into a thin wire without breaking
Eecho
sound that is reflected off a surface echolocation
a method of using sound waves to determine the distance and direction of an object
ecosystem
a community of living organisms and their non-living surroundings
ectotherm
an animal that relies on external sources of heat effector
tissue or organ (i.e. muscles or glands) that produce a specific response to a stimulus
electromagnetic spectrum the full range of frequencies for all waves electron
a negatively charged particle that moves around in the space outside the nucleus emigration
leaving a group or community to join another permanently encoding the conversion of sensory memory into a usable form so that it can be represented and stored in memory endocrine system
a collection of glands that make and release hormones endotherm
an animal that generates its own body heat metabolically enhanced greenhouse effect an increase in carbon dioxide and other heat-capturing gases in the atmosphere, resulting in increased warming of the Earth ephemeral
a type of plant that lasts a very short time, usually completing one or more life cycles a year evaporation
a process that changes a liquid to a gas explanatory model
a simple way to explain what and why something is happening and the relationship between variables extrapolation estimating unknown values from trends in known data
F filter
focal point where light rays meeting after reflection or refraction fodder
dried hay or straw used as feed for cattle and other livestock frequency
the number of waves that pass a point every second; measured in hertz fuel
a substance that undergoes a chemical reaction producing large amounts of energy
G
gamma rays
high-energy electromagnetic rays released as a part of radioactive decay; can be stopped by lead geotropism
the directional growth of a plant in response to gravity; roots are positively geotropic as they grow downwards and towards the pull of gravity, while shoots are negatively geotropic as they grow upwards and away from the pull of gravity greywater
wastewater from non-toilet plumbing systems such as hand basins, washing machines, showers and baths groundwater
water found underground in soil or in the pores and gaps in rock group
a vertical list of elements in the periodic table that have characteristics in common
H
half-life
the time it takes the radioactivity in a substance to decrease by half halogens
herd immunity
when a sufficiently large proportion of a population has been vaccinated that it makes it difficult for a pathogen to spread hertz
the unit used to measure frequency; symbol Hz hippocampus
a central part of the brain responsible for encoding explicit memories homeostasis
DRAFT
a transparent material that allows only one colour of light to pass through filtration
the process by which impurities or particles are removed from a fluid using a filter medium that allows fluid to pass through, but retains any particles focal length the distance between the centre of a lens and the focus
the group of elements in group 17 of the periodic table halophyte
a type of plant that has adapted to survive in environments high in salinity hazard
a dangerous substance or activity that can potentially cause harm or injury hazard reduction burning also known as controlled, planned or prescribed burning; when fire is ignited in a pre-determined area under specific fuel and weather conditions in order to achieve planned fuel management outcomes
the process by which the body detects and responds to stimuli to ensure a stable internal state is maintained hormone
a chemical messenger that travels through blood vessels to target cells hydrocarbons
substances that are made of only hydrogen and carbon hydrophyte
a type of plant that has adapted to grow in water hydrosphere
all the solid, liquid and gaseous waters on Earth that support life hydrotropism
the directional growth of a plant in response to a higher water concentration in the soil hygrophyte
a type of plant that has adapted to live in very moist areas hypothesis
a proposed explanation for a prediction that can be tested
Iimage
a likeness of an object that is produced as a result of light reflection or refraction immigration
joining a new group or community permanently independent variable
a variable (factor) that is changed in an experiment indicator species
a species whose relative presence in an ecosystem can be used to make inferences about the health of that ecosystem infiltration the process of water being absorbed into the ground
inner transition metals
the collection of metallic elements, lanthanides and actinides inorganic compound
a substance consisting of two of more elements other than carbon interneuron
a nerve cell that links sensory and motor neurons; also known as a connector neuron interpolation
estimating unknown values that fall within a certain range of known data intrusion
when upwelled waters do not reach the surface ion
an atom that is charged because it has an unequal number of electrons and protons iris
the coloured part of the eye that surrounds the pupil irrigation
practice of applying controlled amounts of water to land in order to help grow crops and plants isobar
a line drawn on a weather map that joins places of equal air pressure isotope
an atom of a particular element that has more or fewer neutrons in its nucleus than another atom of the same element
Llanthanides
a subset of metallic elements found in period 6 of the periodic table lens
a curved piece of transparent material line transects
a sampling method used where organisms that are on or touch a straight line are recorded lithosphere
M
malleable
a property of a substance that means it can be formed into a variety of shapes mass number
a number that represents the total number of protons and neutrons in the centre of an atom matter
anything that has space and volume; matter is made up of atoms medium
a substance or material through which light can move mesophyte
a type of plant that has adapted to thrive in average conditions metal
a substance, usually solid at room temperature, which is generally hard, shiny, malleable and a good conductor of heat and electricity metalloids
a small collection of elements that have characteristics of metals and nonmetals method
the procedure followed in an investigation to collect data mineral
a naturally occuring element or compound
motor neuron
a nerve cell that carries a message from the central nervous system to a muscle cell
mutualism
a type of relationship between two organisms of different species in which both organisms benefit myelin sheath
a fatty layer that covers the axon of a nerve cell
N
neurotransmitter
a chemical messenger that crosses the synapse between the axon of one neuron and the dendrite of another neuron
neutron
a neutral (no charge) subatomic particle in the nucleus of an atom
noble gases
the stable gaseous elements in group 18 of the periodic table non-metal
a substance, usually in the form of a gas or liquid, which is a good insulator of heat and electricity
DRAFT
the outermost layer of Earth, consisting of the upper mantle and crust long-sighted (hyperopia) where close objects appear blurry as light rays converge behind the retina
long-term memory
a memory store that holds information for an unlimited period of time longitudinal wave
a type of (sound) wave where the particles move in the direction of travel of the wave
natural greenhouse effect the natural warming of Earth due to water vapour and other gases being present in small amounts in the atmosphere
negative feedback mechanism
a regulatory loop in which the stimulus causes a response that acts in the opposite direction to whatever is being regulated
neuron
a nerve cell
normal
(in relation to light) an imaginary line drawn at right angles to the surface of a reflective or refractive material
nuclear equation
an equation that indicates there is a rearrangement of subatomic particles during a nuclear reaction so the total number of atoms of each element are conserved and do not change nucleus
the centre of an atom, containing protons (positive charge) and neutrons (no charge)
numerical data information in the form of numbers
O
observation
the act of carefully watching, usually using the senses to gain information and generate knowledge ocean acidification
the production of carbonic acid in the ocean due to the absorption of carbon dioxide
opaque
not allowing light to pass through opportunistic (in relation to plants) describing plant species that can grow in huge numbers quickly to make use of newly available resources
optic fibre
a thin fibre of glass or plastic that carries information/data in the form of light
optic nerve
the connection between the eye and the brain that transmits visual information
ore
a rock that contains a high percentage of one type of mineral
organic compound
a substance consisting of two or more elements including carbon; most organic compounds also contain hydrogen outlier
a data point that differs significantly from the main group of data
Pparallax error
an error, or inaccurate reading, that occurs as a result of reading a scale from an angle parasitism
a relationship in which one organism (parasite) lives in or on the body of another organism (host) and benefits while the host is harmed pathogen
a microbe that can cause disease pattern
a repeated sequence or arrangement of numbers or data points
peer review
a process in which experts evaluate the findings of a report before it is published percolation
movement of water through soil period
(in relation to chemistry) a horizontal list of elements in the periodic table (in relation to physics) the time taken between two crests or troughs of a wave periodic table
a table in which elements are listed in order of their atomic number, and grouped according to similar properties periodic trend patterns in the properties of elements in the same period or group in the periodic table periodicity
repeating properties in the elements peripheral nervous system all the neurons (nerve cells) that function outside the brain and spinal cord permafrost permanently frozen ground photon
photosynthesis
a chemical process used by plants to make glucose and oxygen from carbon dioxide, sunlight and water phototropism
the ability of a plant to re-orientate shoot growth in response to light plum pudding model
an early model of the atom in which the positively charged nucleus has negatively charged electrons scattered through it, like the fruit in a plum pudding point sampling
a method based on placing a number of points within an area, and determining the proportion of points that meet a specific criteria population
a group of individuals of the same species living in the same location at the same time potable water
water that is safe for human consumption precipitation
water released from clouds in the form of rain, snow or hail precise
how close measurements of the same item are to each other predator
an animal that hunts and feeds on another (prey) for food prediction
an outcome that is expected based on prior knowledge or observation prey
an animal that is hunted and killed by another (predator) for food primary colours of light the three colours of light (red, blue and green), which can be mixed to create white light product
qualitative
data that can be measured using categories quantitative data that can measured numerically
Rradiation
an emission of energy through space or a material medium
radioactive decay
DRAFT
a substance obtained at the end of a chemical reaction; written on the right side of a chemical equation proton
a particle that makes up light and other forms of the electromagnetic spectrum photoreceptors
specialised cells called rods and cones that are responsible for colour vision, vision in low light conditions and motion detection
a positively charged subatomic particle in the nucleus of an atom pupil
the black circular opening in the centre of the eye
quadrat sampling
a method by which organisms in a certain proportion of the habitat are counted directly
the conversion of a radioactive isotope into its stable form, releasing energy in the form of radiation radionuclide
a radioactive isotope
random error
when an unpredictable variation in measurement occurs, resulting in an outlier result rarefaction
a reduction in density; refers to the part of a sound wave where air particles are forced apart
ray diagram
a drawing used to represent the path of light reflecting off mirrors or travelling through lenses reactant
a substance used at the beginning of a chemical reaction; written on the left side of a chemical equation recall
the mental process of retrieving information from the past receptor
a structure that detects a stimulus or change in the normal functioning of the body recognition
a form of remembering characterised by a feeling of familiarity when something previously experienced is again encountered reflex
an involuntary movement in response to a stimulus refracted ray
a ray of light that has bent as a result of speeding up or slowing down when it moves into a more or less dense medium refraction
the bending of light as a result of speeding up or slowing down when moving into a medium of different density refractive index
a measure of the bending of light as it passes from one medium to another
relationship
the connection between variables relative atomic mass
the average mass of an element, including the mass and prevalence of its different isotopes reliable consistency of a measurement, test or experiment reproducible
the ability to repeat and replicate a test exactly resonance when a vibrating object causes another object to vibrate at a higher amplitude resonance frequency the natural frequency where a medium vibrates at the highest amplitude retina
the light-sensitive layer at the back of the eye that converts light into electrical signals retrieval
the act of processing and recovering memory information from storage reverse osmosis
movement of solvent through a semipermeable membrane from solution to solvent by applying external pressure review
a type of memory retrieval where information is retrieved and recalled risk
the chance that someone could be harmed by a hazard risk assessment
analysis of a practical activity to identify any safety hazards and how to manage the risk
Ssalinity
the presence and concentration of soluble salts in a solution, soil or another medium sampling
the process of selecting a sample population from a target population scientific method
sedimentation
process where solid material is moved and deposited in a new location
sensory neuron
a nerve cell that carries a message from a receptor to the central nervous system
sewage
wastewater that is contaminated with faeces or urine
short-sighted (myopia)
where distance objects appear blurry as light rays converge in front of the retina
short-term memory
a type of memory store where we can consciously hold information while we use it or before we transfer it to longterm memory
solar radiation
radiant electromagnetic energy from the Sun
somatic nervous system
the part of the nervous system that controls the muscles attached to the skeletal system
sonar
the detection of the location of objects through the use of sound waves stimulus
any information the body receives that causes it to respond storage
the ability to keep encoded information in the brain
subatomic particle
a particle that is smaller than an atom
subscript
the small number written at the bottom right of a chemical symbol
surface runoff
excess water that cannot be absorbed by the land; tends to flow across the surface of the land to nearby creeks, streams or ponds
symbiosis
tectonic plate
a large layer of solid rock that covers part of the surface of Earth; movement of tectonic plates can cause earthquakes
thermoregulation
a process by which a body maintains its internal temperature
total internal reflection
the complete reflection of a light ray when it passes from a more dense to a less dense material at a large angle; the ray is reflected back into the dense medium
transect sampling
DRAFT
a close physical relationship between two organisms of different species
synapse
a process involving making an observation, forming a hypothesis, making a prediction, conducting an experiment, collecting the data, analysing the results and drawing conclusions
secondary colours of light
the colours of light (magenta, cyan and yellow) that result from the mixing of two primary colours of light
a small gap between two neurons that must be crossed by neurotransmitters systematic error
a repetitive error that is not removed by repeating the experiment
Ttarget cell
a cell that has a receptor that matches a specific hormone
a method used to study the distribution and abundance of organisms along a line or a pathway
transition metals
the elements in groups 3–12 of the periodic table translucent
allowing light through, but diffusing the light so objects cannot be seen clearly
transmit
to allow light to pass through transparent
allowing all light to pass through, so objects can be seen clearly transpiration
the process of water evaporating from plant leaves; causes water to move up through the plant from the roots transverse wave
a type of (light) wave where the vibrations are at right angles to the direction of the wave
trend
represents the overall direction of the data points tropism
the growth or movement of a plant in response to an environmental stimulus
Uuncertainty
a quantitative measurement of variability in data
upwelling
the process in which deep, nutrientrich cold water moves up towards the surface
urban water cycle
ways in which water is collected, used and managed in an urban environment
Vvaccinated to be injected with an inactive or artificial pathogen that results in the individual becoming immune to a particular disease
valence electron the outer-shell electrons of an atom valid
where a test investigates what it sets out to investigate variable something that can affect the outcome or results of an experiment vasoconstriction
narrowing of the internal diameter of blood vessels due to the contraction of their muscular walls vasodilation
widening of the internal diameter of blood vessels due to the relaxation of their muscular walls
virtual focus
the point at which a virtual image appears virtual image
an image that appears in a mirror and cannot be captured on a screen visible spectrum the range of colours in light wavelengths that can be seen by the human eye
Wwater cycle
continuous circulation of water within Earth and the atmosphere wavelength
the distance between two crests or troughs of a wave weather
the temperature, humidity, rainfall and wind at a particular time in a particular place
wind
the sideways movement of air as a result of lower-density warm air rising through the atmosphere
X
xerophyte
a type of plant that has adapted to survive in arid environments
Z
zone of elongation
a region of the root of a plant where newly formed cells increase in length
DRAFT
Index
Aabiotic definition 73 factors 70, 73, 78–80, 88 Aboriginal and Torres Strait Islander Peoples 19 cultural burning 230–1 ecosystem management 93 Indigenous science see Indigenous science absorption chemicals, of 22 accuracy 12 improving 30 parallax errors 30 random errors 29 reading errors 30 significant figures 29 systematic errors 30 zero error 31 actinides 158 adaptations 70 animals see animals plants see plants adrenalin 128 aeration 221 aerobic cellular respiration 224 definition 224 agriculture 92–3 fodder 218 Indigenous science 60 irrigation 218 regenerative 60, 61 revegetation 60–1 salinity, and 96 sustainable 92–3, 312–15 air movement 234–5 alkali metals 157 alkaline earth metals 157 alpha particles 149, 165 amplitude 264, 266 amygdala 305 anaerobic cellular respiration 224 definition 224 analysing 5, 35–8 results see results angle of incidence 279, 284, 295 angle of reflection 279 angle of refraction 284 animals 102 adaptation 102–7
arid ecosystems 103–4 fire-prone ecosystems 104–5 marine ecosystems 106–7 polar ecosystems 105–6 thermoregulation 136, 137 anions 188 annuals 100 antidiuretic hormone (ADH) 133–4 aquatic environments monitoring 88–91 properties, measuring 90 arid ecosystems animal adaptation 103–4 astigmatism 290 atmosphere 206, 209–10 layers 209–10 atomic mass 151–3 isotopes 161–2 relative 162 atomic number 152, 161 mass number, distinguished 152 atomic radius 158 atomic theory 148 atoms 146, 148 electrons 148 elements 150, 161 ions see ions modelling, challenge 160 plum pudding model 148 representation of 152–3 Rutherford’s experiments 149 size of atoms 151 subatomic particles 148 ATP 132 audience 54–5 auditory learners 310 Australian fire beetle (Merimna atrata) 104 authors (secondary sources) 50 autonomic nervous system 120 axon 120
calculations 37–8 mean 37 median 37 mode 37 percentages 37–8 range 37 cancer 146 capture–recapture method 81, 84 carbon cycle 222 bushfires, and see bushfires
carbonic acid 225 cataracts 290 catchment area, definition 96 water 215–16 categorical data 35 cations 188 causation 42 cells cell body 120 target 127
cellular respiration 223, 224 aerobic 224 anaerobic 224 census 81
central nervous system 119–20, 305 cerebellum 305 cerebral cortex 304 cerebrum 304 chalcogens 158 change, responding to see responding to change chemical equations 176, 183 balanced 182–4 coefficients 184
modelling, challenge 191–2 subscripts 184 chemical formulae 186–90 guidelines for writing 186, 187 naming, rules for 187 chemical reactions 176 comparing mass, experiment 181–2 describing 183 Law of Conservation of Mass 176, 178–9 observed changes 183 purification of elements 197–201 representing chemicals 180 word equations, using 183 chemical safety 22–3 absorption 22 disposal methods 23 ingestion 22 inhalation 22 rules 23 chemistry, green 176 citizen science 85 climate deep ocean currents, and 247, 249–51 definition 232 global system 233–5 greenhouse experiment 257–8 human activity, impact of 232–8, 255 weather, distinguished 232 climate change 2, 206, 236 bushfires, and 229 climate models 13 computer modelling 14 disease, and 245–6 evidence 239–40 health, and 245–6 impacts 245–7 key indicators 240–5 Kyoto Protocol 253 mitigation 253–4 modelling 248 research 253 species distribution, and 246–7 coagulation 221 cobolt-60 146 coefficient 184 colour 291–2 complementary colours of light 292 dispersion 291 experiment 293–4 filters 292 opaque objects 292
covalent 194–6 separation of see separation Geiger, Hans 149 geosequestration 254 geotropism 141 glands and organs of the endocrine system challenge 130 global systems 206 human activity, impact of 232–8 global warming 13 glossary 320–6 glowing splint test 195 graphs column 36 data see data extrapolating 42–3 interpreting 40–1 line 36–7 gravity plant growth, and 141 separation 198 greenhouse effect 13 enhanced 236–7 natural 233–4 greenhouse experiment 257–8 greenhouse gases 209 climate change mitigation 253–4 increased concentration 240–1 levels 238 greywater 216 groundwater 214
Hhalf-life 166 dating objects, and 167–9 halogens 158 halophytes 98, 100–1 Hamersley Gorge 19 hazard reduction burn 230
hazards 16 recognising and managing 16 HAZCHEM codes 21 health climate change, impact of 245–6 hearing 114, 115–16 problems 270 sound, and 269–70 heating heat transfer 136–9, 264 herd immunity 14–15 hertz (Hz) 267 hippocampus 305 homeostasis 131–4 definition 131 experiment 135–6 negative feedback mechanism 131 oxygen and carbon dioxide 134 water regulation 133–4 hormones 126–7, 132 blood glucose 132 water regulation 133–4 human impacts carbon cycle, on 226–8 global climate 232–8 salinity 95–6 water management 215–16 hydrocarbons 228 hydrogen detecting, test for 194–5 energy 58 isotopes 162–3 oxygen, reacting with 184 hydrophytes 98, 99 hydrosphere 206, 211 climate, impact on 211 hydrotropism 141 hygrophytes 98, 99 hypothermia 112 hypothesis 9 definition 9
I-ide, suffix 187 ideate
STEAM project 314, 318 image 278 virtual image 279 immigration 79 independent variables 8 indicator species 89 Indigenous science land management 230–1 industry innovation 59 infiltration 214 information, passing on 55
ingestion of chemicals 22 inhalation of chemicals 22 inner transition metals 158 innovation 59 instruments water quality monitoring 90–1 insulators 264 insulin 112 Intergovernmental Panel on Climate Change (IPCC) 239 interneurons 121 interpolation 43 intrusion 250–1 invalid data 48 investigations animals, using 18 data see data ethical issues 17–18 fair test 12 findings, communicating 53–6 people, using 17–18 planning 11 protocols 18–19 repeating 49 results see results scientific reports 53–5 types 12 iodine-131 146 ionic compounds 188–90 naming, rules for 189 writing formulae 189 ionosphere 210 ions 188 anions 188 cations 188 nature of 188 polyatomic 190 iris 288 irrigation 218 isobars 235 isotopes 146, 161–9 atomic mass 162 dating objects, and 167–9 definition 161 hydrogen 162–3 oxygen 163 radiation, and 164–6 radioactive decay 164
Kkinaesthetic learners 310 king penguin ( Aptenodytes patagonicus) 106 Kings Park Plant Development program 255 kites (birds)
black kite (Milvus migrans) 105 whistling kite (Halisastur sphenurus) 105
Kyoto Protocol 253
LLa Niña 250 laboratory safety see safety land use 91–3 historic 93 lanthanides 158 laser surgery 289 Law of Conservation of Mass 176, 178–9 leaching 199 learning 310 auditory 310 brain function 306 kinaesthetic 310 metacognition 311 visual 310 lenses 286–7 concave 286 convex 286 eye lens 288 focal length 286 lens, definition 286 light 264, 275–86 angle of incidence 279, 284, 295 angle of reflection 279 angle of refraction 284 colour, and see colour critical angle 295 dispersion 291 diverge, definition 286 electromagnetic spectrum 275–6 lenses see lenses normal 278 phototropism 141 reflection 278–83 refraction 284–7 Snell’s Law 285 speed of 276 total internal reflection 295–6 visible spectrum 291 wavelengths 276–7, 291–2 limewater test 195–6 line graphs 36–7 line transects 83 lit splint test 195 literacy 302 lithosphere 206, 208–9 living organisms see organisms logbook 2, 32–3
