Technology 2 Student Book sample

DIGITAL PROJECT

DEMO

INCLUDED

RESOURCE BANK DIGITAL BOOK

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2

N O I T A C U D E Y R A D EC O N

y g o l o n h Tec M . P. B l

os J. Sant , s o y o , I. H ázquez

Building

Blocks

this is

your book

Reading and listening

ch unit

f ea The opening Page s o

5

We read and listen about the topic of the unit, learning about key concepts and developments in technology.

Speaking We speak about the different issues relating to the unit and the UN Sustainable Development Goals.

Speaking

4

ELECTRICITY g

Reading and listenin

y use Everyday energ

you think of? The How many can e from in many forms.

Energy comes It’s easy to generat is electrical energy. of energy most versatile type into other forms , simple to convert store in large different sources is not easy to rt. However, it and easy to transpo amounts. everyday life. we use in our is the energy electric energy bulbs, l Electrica ves, light ones, microwa n: they need Computers, smartph thing in commo these have one need to be motors, all of and machines These devices l energy from electricity to work. to receive electrica electric circuit them is connected to an that flows through ty electrici the sound, heat or a generator. Then, of energy: light, different forms transformed into others. movement, among of electrical disadvantages of advantages and think of one more 1 What are the you Can text? ed in the energy mention each? a clue: you transported? Here’s how energy is are out 2 Do you know pylons, when you tall towers, or might have seen side. for. walking in the country use these devices and say what we Would 3 Look at the pictures electricity? How? things without Could you do these time? they take more

save energy a campaign to 11.6, groups, organise read SDGs 7.3, In small and at home. First, and water at school anding. Then, follow check your underst 12.8 and 13.3 and to the steps: and inspire others educate you can how 1 Brainstorm: ? Be creative! realistic be energy efficient most think are the ideas that you like turning off 2 Choose the by anyone at school, and can be done m, or at home. e leaves a classroo create lights when everyon informative posters, campaign: make the actions are 3 Prepare your d to making sure ful it a committee dedicate up how success then later follow implemented, and was.

How about suggesting students…?

We could ask students to...

Writing g be saved by replacin much energy would saving bulbs. with new energy by looking old light bulbs old and new bulbs the price of the many 1 Write down consume? How watts do they online. How many ? do they produce light of live by lumens costs where you much electricity a search engine: 2 Find out how g keywords into putting the followin prices or global energy save energy use calculat energy you could a much money and d on for 6 hours 3 Work out how bulb which is switche with one light m. classroo your in to your day, 5 days a week s, write a letter on these activitie how to 4 Looking back endations on with your recomm head teacher school. save energy at

5 Investigate how

GE BANK GE BANK LANGUA LANGUA BANK GE NK GE BANK GE BA LANGUA LANGUA LANGUA BANK 103 GE BANK GE NK GE BANK GE BA LANGUA LANGUA LANGUA LANGUA BANK GE BANK NK NGUAGE NGUA BA GE LA LA UA

LANG

102 102

The audios of each unit’s content are available at www.anayaeducacion.es

Writing We write a variety of different styles and types of text relating to the unit topic, sometimes relating them to the UN Sustainable Development Goals. By practising different styles of writing, we improve our writing skills we need.

CONTENT DEVELOPMENT Highly structured content with important concepts highlighted in bold.

1

2

ä 1.1 What is an electric circuit?

ELECTRIC CIRCUITS

An electric circuit is a closed path made of wires and components that an electric current can flow through.

Atoms and electrons ––

An electric circuit has the following parts:

➜ A battery or generator, which provides energy for the circuit. ➜ Conductors, which let the electricity go through the circuit from

– –

the generator to the loads.

– –

➜ Loads, which transform the electrical energy into other energy: movement (kinetic energy), light (light energy), and heat (thermal energy), etc.

–

➜ Control elements, such as switches and push buttons. ➜ Protection elements, such as fuses.

Matter is made up of particles called atoms. Atoms are made up of subatomic particles called protons, neutrons and electrons. Protons have a positive electric charge, while electrons have a negative electric charge. Electrons have the smallest electric charge we can find.

Guided practices and Model examples to help you learn new processes.

A circuit must contain a battery or generator, conductors and at least one load element. The control and protection elements are optional.

Load

Because electrons have such a small charge, a larger unit, the coulomb, was defined. A coulomb has an electric charge equivalent to 6.24 · 1018 electrons.

Conductor Generator

Switch

Fuse

Alternating current and direct current There are two kinds of electric current depending on how they are generated:

• Direct

current: supplied by chemical and electric batteries. It has a constant value.

• Alternating current: generated by alternators. Our homes receive this kind of current through the electrical grid*. The direction of the current changes all the time because the voltage of the sockets Programming platforms changes between positive and negative all the time.

The first programming language that contained a translator was FORTRAN. The name is based on the English words FORmula TRANslating System. The project was run by the company IBM at the beginning of the 1950s.

1 COMPUTER LANGUAGE

Today, all program development systems contain a high-level platform which the user programmes their instructions on. There are also a series of modules which contain the programs that do the translating and interpreting, and these are not accessible to the programmer.

Understand, think, investigate...

1

What makes you say that? Which light bulbs do you think will light up in the following circuits? a)

b)

2

Knowledge transfer. Imagine a central heating system with a water boiler that heats the water flowing through the pipes to the radiators.

What similarities are there between the heating circuit and an electric circuit? Which part functions as a generator in the central heating system, and which would be the control elements?

Heating circuit

c)

d)

+

+

Thermal energy

e)

+

Valve

Hot water Cold water

The icons included with some activities indicate the keys to the project.

Unit

ELECTRIC GENERATORS

104

Power supply

Wide variety of pictures grouped according to content to aid your understanding.

5

ä 2.1 Electric generators In an electric circuit, the generator provides the energy for the electric charges which move around the circuit. Generators can be:

➜ Batteries, which generate electricity through chemical processes.

When the chemical substances of batteries allow the reaction to be reversed, the batteries are called rechargeable* batteries.

➜ Alternators are electric machines that produce alternating current.

They generate electricity in the form of waves, which means their voltage and the direction of the current varies.

➜ Power supplies. These are devices that transform alternating current into another form of electrical energy, like direct current.

The value of direct current does not change.

Unit

9

ä 2.2 Electrical voltage Guided practice A generator provides electrical energy to direct the flow of electric current through a circuit. When a generator has no energy, there is no to programming platforms flowAn of introduction electric current.

ä 1.4 Algorithms: the first stage in

Food recipes

programming

Like any other technical project, a computer program is the result of a series of stages of design, development and tests. The first stage is to create an algorithm. An algorithm is basically an ordered set of operations that form the basis of a program.

Two difference, of the mostorpopular languages used schools Voltage electricprogramming potential, is the parameter thatinindicates Scratch and Alice. career as a programmer by howtoday muchare energy is provided toStart eachyour electric charge. visiting the websites of both platforms to give yourself an idea of If a generator supplies 1 joule of energy to a charge of 1 coulomb the kind of programs you can develop. (which is 6.24 · 1018 electrons), we say the generator supplies 1 volt. So, Go to for thethe Scratch website the 1formula voltage wouldby be:searching the keywords: scratch mit edu. Click on the website in the search results and explore Voltage = Energy/Electric Charge ; V = E/Q the platform to see how it works.

Where E is the energy expressed in joules (J), Q is the electric charge expressed in coulombs (C) and V is the voltage expressed in volts (V).

When you create the algorithm, you have a clearer idea of the elements in a program. You have to pay particular attention to the variables in the program, these are elements which will help you to form many of the values you are going to use.

Model example

The volt is a unit of voltage in the International System of Units. Its name is in honour of Alessandro Volta (1745 – 1827), who created the first electric battery. Volts are represented by the letter V.

The French omelette algorithm

F ocus on English the electrical grid: the network which connects consumers of electricity to the producers of electricity rechargeable: describing a battery which can receive a new supply of electrical energy and be used again

Model example 2 Search the keywords: alice org index. Open the search results A desktop computer is connected to the electrical grid that supplies alternating current. However, its circuits work with direct current, so it needs a power supply that transforms the alternating electric current into direct current.

SDG. Reflection on and analysis of SDGs, such as gender equality, climate action, reducing inequalities, etc.

and explore the Alice community website.

What is the voltage of a battery that builds up a charge of 10 coulombs and stores 45 joules of energy?

Solution: A battery of these characteristics has a voltage of: Energy 45 J Voltage = = = 4.5 volts Charge 10 C

You can find resources for this unit at anayaeducacion.es.

A food recipe is like an algorithm, as the processor doing the actions is like the person who is preparing the food. The ingredients are listed in a recipe, and these are like the variables that have to be arranged in the program. A dish always has to be made in the same way, just like a program is always run by following the same programmed steps.

An algorithm is basically a list of steps that need to be followed to get a result. In the case of a French omelette we need a few raw materials, which will be referred to later as input variables. To run a program, we have to initialise the variables. In our analogy, this means we prepare the raw materials first (the egg, oil and salt) so they are ready to make the omelette. The program would have the following steps:

1 Get out your ingredients: the egg, salt and oil.

2 Put a frying pan on the hob*.

3 Turn on the hob.

4 Pour a little oil into the frying pan and spread it all over its surface.

F ocus on English

5 Crack the egg into a bowl.

a pinch of: a small amount of something that you hold between your finger and thumb

6 Remove any shell from the raw egg. Throw away the shell.

hob: the flat top of an oven which can be used to heat frying pans or saucepans in cooking 105

7 Add a pinch* of salt to the egg.

8 Beat the egg until the mixture is even.

9 Pour the mixture into the frying pan.

10 Use a spatula to turn the omelette over and cook the other side.

11 When it turns golden, serve the omelette on a plate.

Understand, think, investigate…

1 3 When you have spent a while looking at each of these programming languages, look for Internet chat forums which discuss them. Make a note of the special features of each of these languages and explain why you think they are so popular.

Did you find it easy to understand how to start working with each of them?

Would you be able to develop an algorithm that describes how an automated robotic vacuum cleaner works? How would you plan the programming? Do you think you should focus the programming on a series of events that might happen to the robot, such as hitting a wall or another obstacle?

2

Snack vending machines work by using a program. In the form of an algorithm, write the sequence of actions these machines require.

Start from when we put coins into the machine and finish at the moment we retrieve our snack from the dispenser.

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199

KEYS

PROJECT

SDG

2

SDG Commitment Discover the Sustainable Development Goals and be an active part of our commitment to make a more equal and liveable world.

Developing thinking Work on strategies for thinking: reflect on the content you are learning, generate ideas, organise them, debate them, explain them…

Cooperative learning Get involved in your learning and participate in the group’s learning; you will find that cooperating improves performance and harmony in the class.

Emotional education Get to know yourself; identify the situations that bring up complicated emotions and manage them with constructive, self-affirming experiences.

NEW SECTIONS

Activities with different cognitive levels to check learning.

resources to choose .

Remember for your portfolio from this unit

Unit

ndido apreTISE ANDloPRAC ajaEWcon REVI trab Drawing materials and tools

and write them down in your notebook. Try to draw a sketch of your arm with the measurements made. Use the auxiliary lines surrounding the sketch to help.

1 What characteristics should a piece of paper have if we want to draw on it using ink? What if we want to make a drawing with millimetric precision?

2

18 The following views are of a part which we want drawn in isometric perspective. Create a grid with the correct angles in order to draw it in that perspective.

B

2 What kind of characteristics do these types of

A

paper have?

Glossary

15 Draw the views of the object below

a) Paper for pencil drawings b) Paper for ink drawings c) Sketch paper

4. STRUCTURES AND MECHANISMS

4. TYPES OF STRUCTURES d) Greaseproof paper

1. STRUCTURES

exoskeletons

biomimicry

A strategy that learns from and copies nature to solve problems in design.

loads

The forces exerted on a surface or body.

static balance

When an object is in equilibrium, and does not move or fall over.

to hardest: beams, or beams connected in triangles. each one by 100 and draw it in your notebook, HB, 6H, F, the 2H, centre B, 6B of an arch, holding the other with stones the surface to scale. Take note of the The stone which is in in position. measurements of your bed, your wardrobe and A line drawn throughbetween a shape,awhich reflects each side.

4 What is the difference dip pen and the a same shape other furniture in your room, divide them by 100, fine-point pen? Describe them and sayor other construction Using triangle shapes toeach give of a building, bridge a strong structure. draw them on card and cut them out. Place the what their common uses are. cut outs in the drawing of your room in different arrangements, then choose the design you like 5 What are the angles on the different set squares? the most and draw it.

Make a list of the angles that can be defined with a Open profiles combination of both elements.

13 What is the difference between a graduated ruler and a scale ruler?

6 What is the main function of an extension bar on a Projections and views of an object compass?

keystone symmetry axis

2. FORCES

triangulation

centre of gravity

An imaginary point in a body of matter where the total weight of the body is thought to be concentrated.

5. PROFILES

Glossary We learn the relevant terms that are underlined in the units with a clear definition.

spring scale

An instrument that measures the force exerted on an object, by pulling down on a spring with its weight.

stress

In physics, this is the physical force or pressure on an object.

C

The hard, paper outer parts of structures which support them and hold them together. The e) Millimetre

Scales metal bodywork of a car, for example.

3 Order the following grades of pencils from softest The main supporting parts of a structure; often a combination of horizontal and vertical of your room in metres. Divide 12 Take measurements

framework

7 The ceramic tiles found in Andalucía are well known

Freehand drawing

Long pieces of heavy wood or metal used in building structures such as housing.

braces

Steel cables that are used to strengthen and support a structure.

16 Explain why a reduction coefficient is used in cavalier perspective.

17 Draw the object represented by the views below in isometric or cavalier perspective:

14 Look at the views of the shape and draw the

and are embedded in the local culture. Choose a geometric tile design from the region and copy it, techniques you have learnt.

I, H or double-T profile using the drawing T profile L profile

3. STRUCTURAL COMPONENTS beams

Perspective

object in cavalier perspective.

U profile

Digital graphics 19

Choose a famous painting such as The Mona Lisa, by Leonardo da Vinci; The Clothed Maja, by Goya, a landscape or a still life and make a freestyle copy using Inkscape. To do so, use an image of the painting in a lower layer and make polygons on top of it using the different tools. When you finish, combine all the polygons and remove the lower layer.

Closed profiles

8 Make a sketch of several objects you use in your school: the pen you normally use the pencil sharpener and scissors.

9 Make a diagram of the square and triangle you use. Remember to add the measurements and the value of the angles of each of them.

Rectangular cross-section

Square cross-section

Round cross-section

Triangular cross-section

10 Say what the differences are between an object drawn in a sketch and the same object drawn in a diagram. Which one offers more information about object?

Thethe point on a lever which balances or turns or lifts something.

6. MECHANISMS fulcrum geometric centre

Braces

The gradual destruction of metal caused by external factors such as exposure to water or pollution. Rust is a well-known example of corrosion.

foundations

A solid layer of bricks, cement or stone that support a building from underneath it.

pillars

Tall posts, often in a cylinder shape, which support a building.

Make a list of the advantages, disadvantages and similarities between them. Think about how easy it is to use the drawing tools and the images you get.

(identified in the figure with the letters A, B, C) The relationship between the diameter of a gear and the number of teeth it has.

46

Beams

corrosion

20 Think about when you used Pinta and Inkscape.

11 Take following measurements body Thethe point that is in the middle of of theyour shape, according to its measurements.

module radius

The distance from the geometric centre of a circle, to any of its sides.

You can find a printable isometric template to help you with your drawings at anayaeducacion.es.

230

231

Focus on English

Remember to check out the learn by playing and Study: Mind Map activities available at anayaeducacion.es.

47

References to any extra resources that can be found in your digital resources.

Expand your English vocabulary by learning new words, phrases and grammar structures which we use when talking about technology.

7 DIGITAL GRAPHICS

Unit

Digital graphics can be made up of picture elements called pixels.

These graphics are known as bitmaps.

There is also another type of digital graphics defined by geometrical lines and elements, and this type is called vector graphics.

ä 7.1 Paint3D and Pinta

Paint3D interface.

Paint3D is a simple graphics programme included in Windows operating systems since 2017, replacing the old Paint programme (Paint is still available but no longer updates). Paint3D allows access to a large gallery of 3D models that can be modified and printed.

ä 6.3 The isometric perspective In this perspective, the three reference axes have an angle of 120° between them. We can use paper with a template of equilateral triangles to make drawing in this perspective easier.

C REATE

Technology Workshop

2

These workshops put the ideas you have learnt in the unit into practice. You will be making things, using different computer programmes and practising your new skills.

History

Z axis X axis

Choose a monument from your favourite period in history and try to draw it in either cavalier or isometric perspective.

Pinta is an open-source* app which can be installed not only in Windows, but also in Linux, Mac and BSD operating systems.

The app is in continual development. It has many tools that are not available in Paint, which are easy to use for drawing and touching up* images without having to use more complicated programmes.

Y axis 120°

Understand, think, investigate…

120° 120°

25 Use Paint, Paint3D or Pinta to draw a landscape like the one in

Pinta interface.

the image on the left. Use the tools you have in the programme to create shapes and fill them. What happens if you want to move or make changes to the objects you have drawn?

26 Search in the menus of the drawing programmes you are using and look for the way to re-size the canvas to 1024 Ò 768 pixels. Write how you did this in your notebook.

27

Search online for other free programmes like Paint. Note the operating systems they are available on and the size of the file download.

MAKE A SOUND BOX

28 Go to a website like https://www.pexels.com/ where you can download copyright-free images free of charge. Look for an image you like. Use the filters in Pinta to get images like those below, using the original image you downloaded.

F ocus on English

Original

Brightness setting

Pencil sketch

Ink sketch

open-source: software that is free of charge and available for anyone to make changes to touching up: correcting or making better in appearance

Unit

kshop

Technology wor We do not usually apply any reduction when drawing in isometric perspective, and the proportions on the three axes stay the same.

However, the rule says a 0.82 reduction should be applied to all axes. This way it looks like the real object and keeps the proportions between the axes the same.

24 Think about drawing in isometric perspective.

What length line would you have to draw for each side of a cube if each of its edges measured

2 Saw a central circle in the piece that will be

project presentation

Have you heard the sound of a guitar or violin when the strings are plucked? The sound comes from their vibration, but it is made louder because the instruments have a resonance chamber. String instruments are hollow and the empty space inside them makes the sound more intense.

materials and tools

You are going to make a sound box. To make a sound box of any size you will need a variety of materials. The main material will be the board used to make the box, or resonance chamber. You can use 5-8 mm thick plywood, 3-4 mm thick MDF, or even cardboard, which makes the task quicker and easier. You will also need the following materials:

• Wood glue to join the pieces together. Or hot glue which takes less

Understand, think, investigate…

time to dry.

• Strips of soft wood with a cross section of 10 mm Ò 10 mm.

10cm in reality? Remember what you learnt about the reduction coefficient of the isometric axes. What if it were in cavalier perspective?

• Threads made of different materials like nylon, fishing line, sewing thread, rubber bands, etc.

• Four wood screws with a maximum length of 10 millimetres.

42

• A compass to draw circles.

41

• A fretsaw with a blade for cutting wood, or a box cutter if you are going to use cardboard.

• A glue gun for hot glue.

Create

project steps

1 Mark your measurements and cut six square or rectangular pieces of plywood board to make a cube or rectangular box.

In this section we create a cross-curricular project that joins Technology, Programming and Robotics with other subjects.

Have you ever thought about how Technology, Programming and Robotics can be useful in Science?

Enterprising culture Trust in your skills and knowledge, develop creativity, adapt to changing situations and have a proactive and responsible attitude.

2

used as a cover. To do this, drill a hole then put the fretsaw blade into the hole and tighten it. Now you can cut out the circle shape using the fretsaw.

3 To make the bridge to attach your strings, cut two blocks from a strip of wood. They need to be a bit shorter than the width of the box cover. Place four screws along each block, with equal spaces between them, and screw them in.

4 Attach the two blocks to the top of the box on either side of the circle.

Make sure they are parallel to each other and also parallel to the edges of the box.

5 Put all the pieces together to make the box. Depending on what material you have used for your box, use glue, or nails. To make it stronger, you could reinforce the corners with more wood strips.

6 Finally, place the four different threads between pairs of screws, stretching from one bridge to the other.

Tighten them with a knot and seal the edges.

INVESTIGATE Lots of musical instruments are made from natural wood, but Stradivarius string instruments are probably the most famous. Many experts believe Stradivarius violins are the best, and the sound they produce is the highest quality. One of the secrets to their quality is the type of wood used to make them. Research what they were made of and how they were made.

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Academic and professional

ICT

orientation

Assessment

Linguistic Plan

Learn how to obtain information, select it and apply it; to plan, manage and work on projects; to collaborate online in an ethical and safe manner.

Evaluate your personal skills, discover and awaken your calling, train yourself to make decisions and learn to choose between different options.

Discover different strategies to analyse what you have learnt and how you learnt it; train yourself to take responsibility or overcome difficulties.

Use your communication skills in the different types of text that you will see.

Language is always present, communicate!

3

RESOURCE BANK www.anayaeducacion.es digital book resource bank

Register at www.anayaeducacion.es to access your resource bank or download your digital book. You just need an email address, the code from the inside cover this book and permission from your parent or legal guardian.

A digital version of your book to be used online or offline. It offers access to your digital resources which are grouped by type or linked to unit content.

A space with resources, techniques and activities, designed to strengthen your knowledge.

More about the keys

Resources related to THE project keys SDG

SDG Commitment with short videos that will help you understand the targets for reaching the Sustainable Development Goals worked on in this project.

Linguistic Plan with infographics that will give you models to work with the four linguistic skills, using different text types (descriptive, narrative, explanatory, etc.).

Cooperative learning Preparing for the task In small groups, of four or five members: 1 All the members of the team will review how the assigned task can be accomplished.

2 To do this, the steps can be shared out to each team member who then in turn will explain how each part of the process can be done to the others. The others listen and participate if they think they can contribute something.

Authorship / adaptation : Variant of the Educational Innovation Laboratory of the colegio Ártica - David and Roger Johnson.

Developing thinking with explanations on how to apply the different thinking techniques proposed in the project.

3 Once everyone is in agreement on how to do each part, you will all complete the tasks and, finally, verify, among everyone, that you have solved it correctly.

Cooperative learning which includes descriptions of the cooperative learning techniques proposed in the project.

Thinking techniques

Emotional education with resources to help you overcome any worries that may arise in different situations at school (beginning the school year, taking a test, etc.).

Logic Wheel This thinking technique will help you to establish phases when analysing specific content that you have to study.

Identify What is it? What is it like? Are there different types?

By following a logical sequence (the logic wheel), and by asking yourself a series of questions in each phase, you can:

1

• Identify content by asking yourself: What is it? What is it like?

Are there different types?

• Compare the content by formulating questions such as: In what way is it similar to ...? In what way is it different from ...?

• Establish cause-effect relationships by asking yourself questions such as: Why? What impact does it have ...?

• Argue, assess and ask yourself questions such as: What conclusions can be drawn after the analysis? What can be assessed or scored about it?

Doing a data dump of these questions into a graphic organiser will help you.

Authorship: Hernández, P., and García, L. A.; adapted by Escamilla, A.

Compare

Argue, assess What can we conclude?

4

Logic wheel

2

3 Establish cause-effect relationships Why? What impact does it have ...?

In what way is it similar to ...?

In what way is it different from ...?

ICT resources to help you use information and communication technology in a healthy, correct and safe way.

Academic and professional orientation with information on different professions linked to the subject content.

Assessment which includes resources for your portfolio, as well as rubrics and targets that will help with your self-assessment.

Resources

Subject key concepts Additional content

What you need to know Simulations Learn by playing Videos and tutorials Language bank

Resources classified

by unit

All the resources are classified by unit so that you can find them more easily.

5

COURSE CONTENTS

1

TECHNOLOGY AND SOCIETY’S PROGRESS

Page 8

4

structures and mechanisms

Page 78

Our relationship with the planet ....................................... 8

A world of constructions ...................................................... 78

1. Our progress through technology ................................ 10

1. Structures ............................................................................... 80

2. The repercussions of technical activity ....................... 11

2. Forces ....................................................................................... 83

3. The impact of technology on the environment ....... 12

3. Structural components ...................................................... 87

4. Problem solving in technology ....................................... 16

4. Types of structures ............................................................. 89

5. The technology workshop and project work ............ 21

5. Profiles ..................................................................................... 91

Technology workshop. Make a budget ........................... 25

6. Mechanisms ........................................................................... 93

Review and practise. ............................................................. 26

Technology workshop. Lightweight structures.

Making pulleys ............................................................................ 98 Review and practise ................................................................ 100

2

Technological product Design

Page 28

Technology and drawing .............................................................. 28 1. Graphic communication: A universal language ....... 30 2. Drawing tools and materials ............................................ 31 3. Freehand drawing ............................................................... 35 4. Scales ....................................................................................... 36 5. Projections and views ........................................................ 37 6. Perspective ............................................................................ 39 7. Digital graphics .................................................................... 42 Technology workshop. Signs in public places.

Technology workshop signs ................................................ 44 Review and practise ................................................................ 46

5

electricity

Page 102

Everyday energy use .............................................................. 102 1. Electric circuits .................................................................... 104 2. Electric generators ............................................................. 105 3. Conductors and insulators .............................................. 106 4. Electrical loads .................................................................... 107 5. Control and protection elements ................................. 109 6. Circuit symbols .................................................................... 110 7. Electrical resistance ........................................................... 111 8. Electric power ...................................................................... 112 9. Different circuit connections ......................................... 113 10. Energy sources..................................................................... 117 11. How electrical energy is generated and transported ........................................................................... 120

3

Materials in technology: Wood and metals

12. Energy efficiency ................................................................ 122 Page 48

Technology workshop. Electrical measurements ........ 124 Review and practise ................................................................ 126

Sustainability in the materials industry .......................... 48 1. Materials ................................................................................. 50 2. Properties of materials ..................................................... 51 3. Wood ....................................................................................... 52 4. What do we use wood for? ............................................ 55 5. Woodworking tools ........................................................... 58 6. Metals ...................................................................................... 62 7. Ferrous metals ..................................................................... 65 8. Non-ferrous metals ............................................................ 67 9. Metalworking tools ............................................................ 68 10. Working with metal ........................................................... 70 Technology workshop. Make a sound box ..................... 74 Review and practise ................................................................ 76

6

HARDWARE and operating systems

Page 128

A programmable world ......................................................... 128 1. Computer components ..................................................... 130 2. The central processing unit ............................................. 132 3. Peripherals .............................................................................. 136 4. Operating systems .............................................................. 140 Technology workshop. Smart purchases ........................ 146 Review and practise ................................................................ 148

7

SOFTWARE and applications

Page 150

Software in our day-to-day lives ....................................... 150 1. Application software .......................................................... 152 2. Word processors .................................................................. 154 3. Electronic presentations ................................................... 162 Technology workshop. Organising an information technology classroom. Installing Ubuntu ....................... 170 Review and practise ................................................................ 172

8

THE INTERNET

Page 174

A network of knowledge ........................................................ 174 1. What is the Internet? .......................................................... 176 2. Are there risks when using the Internet? ................... 177 3. How does the Internet work? .......................................... 178 4. The Web and HTTP protocol ........................................... 179 5. Email ......................................................................................... 182 6. The social web ...................................................................... 184 7. Internet of things ................................................................. 186 8. Cloud computing ................................................................. 187 9. The Internet and the law ................................................... 188 Technology workshop. Make your first website with Blue Griffon ....................................................................... 190 Review and practise ................................................................ 192

9

INTRODUCTION TO PROGRAMMING

Page 194

Programmable machines ...................................................... 194 1. Computer language ........................................................... 196 2. Programming with Scratch ............................................. 202 3. Creating apps with App Inventor ................................. 209 Technology workshop. Distributing an app .................. 220 Review and practise ................................................................ 222

Glossary ..............................................................................

224

5

ELECTRICITY Reading and listening

Everyday energy use Energy comes in many forms. How many can you think of? The most versatile type is electrical energy. It’s easy to generate from different sources, simple to convert into other forms of energy and easy to transport. However, it is not easy to store in large amounts.

Electrical energy is the energy we use in our everyday life.

Computers, smartphones, microwaves, light bulbs, electric motors, all of these have one thing in common: they need electricity to work. These devices and machines need to be connected to an electric circuit to receive electrical energy from a generator. Then, the electricity that flows through them is transformed into different forms of energy: light, sound, heat or movement, among others.

1 What are the advantages and disadvantages of electrical energy mentioned in the text? Can you think of one more of each?

2 Do you know how energy is transported? Here’s a clue: you might have seen tall towers, or pylons, when you are out walking in the countryside.

3 Look at the pictures and say what we use these devices for.

Could you do these things without electricity? How? Would they take more time?

102 102

Speaking

4

In small groups, organise a campaign to save energy and water at school and at home. First, read SDGs 7.3, 11.6, 12.8 and 13.3 and check your understanding. Then, follow the steps: 1 Brainstorm: how can you educate and inspire others to be energy efficient? Be creative!

2 Choose the ideas that you think are the most realistic and can be done by anyone at school, like turning off lights when everyone leaves a classroom, or at home.

3 Prepare your campaign: make informative posters, create a committee dedicated to making sure the actions are implemented, and then later follow up how successful it was.

How about suggesting students…?

We could ask students to...

Writing

5 Investigate how much energy would be saved by replacing old light bulbs with new energy saving bulbs.

1 Write down the price of the old and new bulbs by looking online. How many watts do they consume? How many lumens of light do they produce?

2 Find out how much electricity costs where you live by putting the following keywords into a search engine: energy use calculator global energy prices 3 Work out how much money and energy you could save with one light bulb which is switched on for 6 hours a day, 5 days a week in your classroom.

4 Looking back on these activities, write a letter to your head teacher with your recommendations on how to save energy at school.

NK E BANK A B E G A ANGU LANGUAG L ANK ANK GE BANK B B E E G G A A U U GUA K LANG ANG N L A L AN GE BANK 103 ANK GE BANK B B E E G G A A U U G A LAN LANG LANGUA LANGU

1

ää 1.1 What is an electric circuit?

ELECTRIC CIRCUITS

An electric circuit is a closed path made of wires and components that an electric current can flow through.

Atoms and electrons ––

An electric circuit has the following parts:

➜➜ A battery or generator, which provides energy for the circuit. ➜➜ Conductors, which let the electricity go through the circuit from

– –

the generator to the loads.

– –

➜➜ Loads, which transform the electrical energy into other energy: movement (kinetic energy), light (light energy), and heat (thermal energy), etc.

–

➜➜ Control elements, such as switches and push buttons. ➜➜ Protection elements, such as fuses.

Matter is made up of particles called atoms. Atoms are made up of subatomic particles called protons, neutrons and electrons. Protons have a positive electric charge, while electrons have a negative electric charge. Electrons have the smallest electric charge we can find.

A circuit must contain a battery or generator, conductors and at least one load element. The control and protection elements are optional.

Load

Because electrons have such a small charge, a larger unit, the coulomb, was defined. A coulomb has an electric charge equivalent to 6.24 · 1018 electrons.

Conductor Generator

Switch

Fuse

Understand, think, investigate...

1

What makes you say that? Which light bulbs

do you think will light up in the following circuits? a)

b)

2

Knowledge transfer. Imagine a central

heating system with a water boiler that heats the water flowing through the pipes to the radiators.

What similarities are there between the heating circuit and an electric circuit? Which part functions as a generator in the central heating system, and which would be the control elements?

Heating circuit

c)

d)

+

+

Thermal energy

e)

+

Valve

Hot water Cold water

104

You can find resources for this unit at anayaeducacion.es.

2 ELECTRIC GENERATORS Alternating current and direct current

Unit

5

ää 2.1 Electric generators In an electric circuit, the generator provides the energy for the electric charges which move around the circuit. Generators can be:

➜➜ Batteries, which generate electricity through chemical processes.

When the chemical substances of batteries allow the reaction to be reversed, the batteries are called rechargeable* batteries.

There are two kinds of electric current depending on how they are generated:

➜➜ Alternators are electric machines that produce alternating current.

• Direct

➜➜ Power supplies. These are devices that transform alternating

current: supplied by chemical and electric batteries. It has a constant value.

• Alternating current: generated by alternators. Our homes receive this kind of current through the electrical grid*. The direction of the current changes all the time because the voltage of the sockets changes between positive and negative all the time.

They generate electricity in the form of waves, which means their voltage and the direction of the current varies. current into another form of electrical energy, like direct current.

The value of direct current does not change.

ää 2.2 Electrical voltage A generator provides electrical energy to direct the flow of electric current through a circuit. When a generator has no energy, there is no flow of electric current.

Voltage difference, or electric potential, is the parameter that indicates how much energy is provided to each electric charge.

If a generator supplies 1 joule of energy to a charge of 1 coulomb (which is 6.24 · 1018 electrons), we say the generator supplies 1 volt. So, the formula for the voltage would be: Voltage = Energy/Electric Charge ; V = E/Q Where E is the energy expressed in joules (J), Q is the electric charge expressed in coulombs (C) and V is the voltage expressed in volts (V).

The volt is a unit of voltage in the International System of Units. Its name is in honour of Alessandro Volta (1745 – 1827), who created the first electric battery. Volts are represented by the letter V.

Power supply

F ocu s on Eng lish the electrical grid: the network which connects consumers of electricity to the producers of electricity rechargeable: describing a battery which can receive a new supply of electrical energy and be used again

Model example A desktop computer is connected to the electrical grid that supplies alternating current. However, its circuits work with direct current, so it needs a power supply that transforms the alternating electric current into direct current.

What is the voltage of a battery that builds up a charge of 10 coulombs and stores 45 joules of energy?

Solution: A battery of these characteristics has a voltage of: Energy 45 J Voltage = = = 4.5 volts Charge 10 C

105

3 CONDUCTORS AND INSULATORS

Not all materials react to an electric current in the same way. Some materials allow the current to pass through them and are used to conduct the current. Others, called insulators, do not let the current pass through, and are used to stop it from reaching places where it mustn’t go.

Type

Guided practice Look at the circuit in the picture.

You can see a battery connected to a light bulb with a spoon connected between them. Repeat the experiment by connecting objects made of different materials between the battery and the light bulb. If the light bulb lights up, the material you added to the circuit is a conductor, but if the light bulb switches off, you have connected an insulator. Start by testing the following objects: a copper cable, a piece of tubing, a pencil, a piece of glass, an eggshell, a piece of lemon, and water.

Characteristics

Examples

Conductors

Low resistance to the flow of an Metallic materials. electric current.

Insulators

High resistance to the flow of an Paper, electric current. glass.

Semiconductors

They can behave like conductors Elements such as germanium or insulators depending on and silicon for making diodes, external aspects. transistors etc.

plastics,

ceramics,

ää 3.1 Electric current in conductors Electric current is the movement of electric charge along a conductor in a closed circuit with a generator. The charges move, creating a flow of electric current through the conductors. It is a continuous and ordered movement of electrons through the different circuit elements.

To find out if the flow is low or high, we can measure the charge that passes through a particular point of the circuit in a unit of time.

This is known as electric current. As a mathematical formula, this is expressed as: Electric current = Charge/Time ; I = Q/t If the electric charge is measured in coulombs, and time is measured in seconds, then the current is measured in coulombs per second. This unit was given the name: ampere.

The ampere is a unit of current in the International System of Units and was given its name in honour of André Marie Ampère (1775 – 1836). Ampère invented the galvanometer: a device used to measure electric current. The ampere is represented by the letter A.

Understand, think, investigate...

3 How much energy does a car battery of 12 volts store if it has a charge of 600 coulombs?

4

106

Intuition and deduction. Air is an insulator

(electricity does not flow from one terminal to another in a plug socket), but electricity in a lightning bolt goes through the clouds and reaches the ground. How can we explain this phenomenon?

5 What charge does a generator produce if 360 coulombs circulate in two minutes? What if 4 coulombs flow in the same time?

6 Look at some electrical appliances at home. What insulation elements do they have? Which parts of these appliances need to be insulated? What materials are they made of?

4 ELECTRICAL LOADS

Unit

5

Loads are elements that receive electrical energy and turn it into other kinds of energy. They have a common property known as electrical resistance, which is their opposition to the flow of electric current travelling through them.

Let’s revise the main kinds of loads in electric circuits.

ää 4.1 Lights ➜➜ There are many devices that turn electrical energy into light. Light bulbs are the most common. Nowadays, light-emitting diodes (LED) are commonly used to provide lighting. LEDs are made with semiconductor materials and use very little electricity.

Types of light bulbs • Incandescent and classic halogen light bulbs. These light bulbs are not the best for saving electricity and they have a short life. It is now illegal to make and sell them in the European Union (except those in stock from before August 2018). They are glass globes with an incandescent filament inside. Halogen light bulbs have halogen gas inside.

• Special halogens. These light bulbs are not good for saving electricity and they have a short life (around 2 000 hours of use). They are glass globes containing halogen gas with an incandescent filament. These light bulbs are used to light ovens, and also have other uses at high temperatures.

• Fluorescent tube. These use 50 to 80 % less energy than the old incandescent bulbs.. They have a long life, but this depends on the number of times they are switched on and off. The tubes contain a small amount of mercury vapour and an inert gas, usually argon or neon. When the electric current flows through, it ionises the gas causing it to glow. This is because it has fluorescent properties.

• Compact fluorescent light bulb (energy-saving). The use and properties of this light bulb are like those of a normal fluorescent light bulb. This type of light bulb has a long life and uses between 50 to 80 % less energy compared to the old incandescent ones. These light bulbs do not need starters and their base is like those of incandescent light bulbs. They light up gradually and must be taken to special recycling centres because they contain mercury vapour.

• LED light bulb. They are very efficient and use 90 % less energy compared to older incandescent ones. They also have a long life of up to 25 000 hours. These light bulbs are made of semiconductor materials that use less electricity.

107

4 ELECTRICAL LOADS F ocu s on Eng lish pump: a machine that forces liquid into or out of something

ää 4.2 Heat emitting elements These devices that turn electrical energy into heat energy are based on the Joule effect: when electric current flows through a conductor, part of the electrical energy is turned into heat energy. Some everyday examples are toasters, water heaters and electric ovens.

Heat can travel in three different ways: by conduction, by convection and by radiation. There are different types of heaters based on how heat is transmitted.

➜➜ Heat is transmitted by conduction when two objects at different temperatures come into contact. A clothes iron is a device that transmits heat by conduction.

➜➜ Heat is transmitted by convection through a fluid (liquid or gas) which conducts heat to places with a different temperature. A hair dryer is a device that transmits heat by convection.

➜➜ The transfer of heat by radiation depends on the temperature inside an object. If the object is hotter than the air around it, the radiation is stronger. There are many heaters that work using heat radiation: infrared, halogens, quartz etc.

Infrared heater.

ää 4.3 Motors and elements that move Electric motors turn electrical energy into mechanical energy. This comes from the force generated by the copper conductor of a motor as it moves inside the magnetic field generated by the magnets of the motor.

Electric motor.

In a technology workshop, the most commonly used loads that produce movement are direct current motors.

Speaker.

Electromagnetic relay.

There are many electric appliances in our homes that contain parts designed to generate movement: pumps* for washing machines and dishwashers, blenders and juicers. Some of them use direct current and others use alternating current.

ää 4.4 Other loads Think about objects that transform electrical energy into other kinds of energy that we have not mentioned above. These include speakers, buzzers and bells.

Understand, think, investigate...

7

108

Generate-Classify-Relate-Develop. Make a

list of the rooms in your house and make a note of the electrical appliances there are in them. Write in your notebook what transformation of energy happens in each appliance. If they transform electricity into heat, do they use conduction, convection or radiation?

Find out if they have motors or pumps, and which type of current they use in order to work. Are there any that use electrical energy to perform more than one function? Classify them depending on the type of transformation and see if they use any of the same parts.

5 CONTROL AND PROTECTION ELEMENTS Open and closed circuits We say that a circuit is closed when all its elements are connected and the electric current flows through them.

In contrast, when a circuit is open, the current does not flow through the elements in the circuit. This can be because one of the elements is disconnected or broken, or because a control element is open.

Unit

5

Control elements are parts designed to allow or stop an electric current from flowing through all or part of a circuit. There are three main types: switches, push buttons and multiway switches.

ää 5.1 Switches Switches are used for opening or closing a circuit. When we turn a light on or off in our bedroom, we use a switch. Another common household example is when we turn the oven extractor fan on or off.

ää 5.2 Push buttons These work in a similar way to switches, but the difference is that they only open or close an electric circuit while they are being pushed.

There are two kinds of push button:

• Normally open push buttons, N.O. • Normally closed push buttons, N.C. Everyday examples include intercom or doorbells that are activated only while the button is being pushed.

ää 5.3 Multiway switches Closed circuit: lightbulb on.

Multiway switches are different to switches. Switches only control the flow of electric current through one line of a circuit, but a multiway switch changes the connection between two circuits. With a single movement of the switch, they open one circuit and close another.

Then, by switching it back to its original position, it closes the open circuit and opens the one that was closed.

They look like normal switches on the outside. Everyday examples are switches that turn lights on and off in a corridor and other rooms from two different points.

Open circuit: lightbulb off.

A switch and circuit diagram with a switch.

+ V

Test yourself with the game ‘Guess the electrical component’ at anayaeducacion.es.

109

6 CIRCUIT SYMBOLS

As with most technical activities, it is important to able to represent electrical circuits in a drawing or diagram. This helps us define an electric circuit, and means others can identify its parts.

To be able to understand a diagram representing an electric circuit, we need to know the symbols used for the generators, conductors, loads, switches and push buttons.

Look at the following table and try to memorize the different circuit symbols for each element.

Type Battery

Rechargeable battery

Image

Symbol

+

–

+ – + –

Alternator

Connecting wire

Resistor

Light bulb

Buzzer

Motor

M

Switch

N.O. push button

N.C. push button

Multiway switch

Fuse

110

See the presentation ‘Examples of circuits and their diagrams’ at anayaeducacion.es.

7

Unit

ää 7.1 The concept of electrical resistance

ELECTRICAL RESISTANCE

Electrical resistance is the level of difficulty an electric current encounters as it flows through an object or material.

Ohm’s law triangle V =I·R

V I

V R V R= I I=

R

5

Based on this opposition, materials are classified as either conductors, insulators, semiconductors or superconductors. The electrical resistance of an object depends on what it is made of and its size.

Electrical resistivity is a physical property of materials that lets us know if they are good or bad conductors. A higher resistivity in a material means it is not very good at conducting electricity.

The unit of resistance in the International System of Units is called the ohm and is represented by this symbol: Ω.

ää 7.2 Ohm’s law Model example Calculate the current that circulates through a 100 Ω light bulb if it is connected to a 5 V battery.

Solution: V 5V = = 0.05 A = 50 mA I= R 100 Ω Calculate the voltage necessary to connect a resistor of 3 Ω, so that a current of 1.5 A can flow through it.

Solution: V = I · R = 1.5 A · 3 Ω = 4.5 V Calculate the value of resistance through which 0.25 A circulates when connected to a 9 V battery.

Solution: R=

V 9V = = 36 Ω I 0.25 A

In the 18th century, a German scientist named Georg Ohm discovered the link between the three electrical measurements of current, voltage and resistance. He stated a law which is now named after him: The current in an electric circuit is directly proportional to the voltage applied and inversely proportional to the resistance of the circuit.

This is mathematically expressed in the following formula: I = V/R You can find out the voltage and resistance by rearranging the formula above, or with the help of the Ohm’s law triangle.

The voltage value will depend on the battery or the power supply.

The current will be low if the resistance of the circuit is high, and it will be high if the resistance of the circuit is low. High current values can cause damage to a circuit. To avoid this, protective elements like breakers or fuses should be connected.

Measurement

Symbol

Unit

Unit symbol

Current

I

Ampere

A

Voltage

V

Volt

V

Resistence

R

Ohm

Ω

Understand, think, investigate...

8 Calculate the resistance in ohms if a 0.5A current

10 What current would circulate through a 90 Ω

is circulating while connected to a 24 V battery.

Show your calculations in your notebook.

lightbulb if it were connected to a 4.5 V battery?

9 What voltage should we connect a 100 Ω bulb to for a 1.2A electric current to circulate through it?

Show your calculations in your notebook.

11

Intuition and deduction. Imagine two

circuits with the same resistance. The first circuit has double the electric current. Will the voltage be the same in the second circuit?

You can practice working with Ohm’s law in the virtual laboratory at anayaeducacion.es.

111

8 ELECTRIC POWER Standby

All electric appliances use electrical energy when we use them. The amount of energy they use depends on the electric power they need.

Electric power is the quantity of energy used during a specified time. The unit of measurement used is the watt (W), which is defined as the consumption of one joule of energy per second: 1W=1J/1s Although the joule is the unit of measurement of energy in the International System of measurements (SI) , another unit is used to measure electrical energy: kilowatt-hour (kWh). To easily calculate the energy consumed, multiply the power in kilowatts by the number of hours that a device is in use.

Standby is when a device is plugged in but waiting to be switched on. The device only uses a small amount of electricity on standby, but you should completely disconnect it from an electric current if you are not using it. This prevents wasting electricity.

Did you know that electric devices on standby can add up to 10 % of the total electricity used in a home?

Check how many devices spend most of the time on standby at home.

The power value of an electric appliance is displayed on a label on its back or base. For example, light bulbs usually have this information on a sticker on the bulb.

The table below compares the power of different types of light bulb which provide the same amount of light.

Type of light bulb

Equivalent light output

Incandescent

40 W

60 W

75 W

100 W

Halogen

22 W

35 W

47 W

60 W

Energy-saving

9W

11 W

15 W

20 W

LED

5W

8W

10 W

13 W

Model example A 60 W light bulb is switched on for 3 hours every day for a week. How much energy in kWh was used in that period?

Solution: Calculate the number of hours the light bulb was switched on: 7 days Ò 3 h/day = 21 hours The power in kW will be: 60 W ÷ 1000 W/kW = 0.06 kW Apply the formula: E = 0.06 kW · 21 hours 8 E= 1.26 kWh

Understand, think, investigate...

12 Calculate the amount of electricity these electrical appliances use in kWh over a period of 30 days: a) a 150 W television switched on for 3 hours every day. b) an 800 W washing machine used for 1.5 hours every day. c) a 100 W computer switched on for 4 hours every other day.

112

9

Unit

DIFFERENT CIRCUIT CONNECTIONS Connecting resistors in series Connecting two resistors in series R1

R2

Connecting three resistors in series R1 R2 R3 Connecting n resistors in series R1 R2

Rn

5

ää 9.1 Circuit connections and equivalent resistance

Electric circuits usually have more than one resistor. A resistor is an electrical component that opposes the flow of electric current, and can be used to protect or control a circuit. These resistors can be connected in different ways which creates different types of circuits.

Equivalent resistance is the total resistance in a circuit. Let’s look at different ways to calculate the equivalent resistance. It will depend on how we connect the resistors to each other.

ää 9.2 Series circuits In series circuits, resistors are connected together one after another.

The problem with this is that if one of the resistors stops working, the others stop too because the current cannot flow through it.

The total resistance produced by all the resistors is the same as adding up the resistance of all of them, according to the formula: Rt = R1 + R2 + … + Rn The total or equivalent resistance of two resistors with 3 Ω and 5 Ω connected in series will have a resistance of: Rt = R1 + R2 = 3 Ω + 5 Ω = 8 Ω In a series circuit, the current flowing through all the elements is the same. This is equal to the current provided by the generator.

However, the voltage is split between the different elements, meaning that the energy provided by the generator is shared across all the resistors in the circuit.

The voltage can be calculated at each point of the circuit by multiplying the value of the current by the value of the resistor.

If all the voltages of the resistors are added together, the result must be equal to the value of the battery or generator.

Measurement

Explanation

Formula

Equivalent resistance

The addition of the resistances of the resistors in the circuit.

Rt = R1 + R2 + ... + Rn

Voltage

The voltage provided by the battery is distributed among the different resistors. So, the Vgen = V1 + V2 + ... + Vn addition of the voltages of the resistors must be the same as the voltage of the generator.

Current

Since there is only one path for the current, it will be the same for all the elements in the circuit.

I = I1 = I2 = ... = In

113

9 DIFFERENT CIRCUIT CONNECTIONS

Model example In the circuit in the diagram, calculate:

Labelling circuits

3X

a) the equivalent resistance.

+

In electric circuits we usually write subscripts, or small numbers below the voltages (V) and current (I) to show that they flow through a certain component.

For example:

b) the total current flowing through the circuit.

• I is the current provided by the battery

d) the voltage drop in each resistor.

• I1 is the current that flows through the first resistor

c) the current flowing through each resistor.

It is shown in the same way for voltages:

• V is the voltage of the battery • V1 is the voltage drop in the first resistor

• V2 is the voltage drop in the second resistor

7X

Solution:

The equivalent, or total, resistance is the sum of* the resistances: Rt = R1 + R2 = 3 Ω + 7 Ω = 10 Ω

• I2 is the current that flows through the second resistor

10 V

To calculate the current, we apply Ohm’s law by dividing the voltage by the equivalent resistance: I = V = 10 V = 1 A Rt 10 Ω Since the resistors are connected in series, the same current flows through all of them.

I = I1 = I2 = 1 A To calculate the voltage drop of each resistor we need to apply Ohm’s law to each one of them: V1 = I1 ∙ R1 = 1 A ∙3 Ω = 3 V V2 = I2 ∙ R2 = 1 A ∙7 Ω = 7 V The sum of the voltage drop in both resistors must be equal to the voltage of the battery, as you can see: V = V1 + V2 = 3 V + 7 V = 10 V

Understand, think, investigate...

13 Calculate the equivalent resistance of the following groups of resistors:

a)

b)

c)

10

e)

5

f) 1

7

4

4

2

3

4

5

3

4

5

3

2

g) 2

1

6

14 If each of the groups in the previous activity were connected to a 9V battery, calculate: a) The current the battery provides.

d)

114

4

4

b) The current circulating through each resistor. c) The voltage of each resistor.

You can practise building series and parallel circuits using the circuit construction kit simulator available at anayaeducacion.es.

Unit

Connecting resistors in parallel R1

5

ää 9.3 Parallel circuits In a parallel circuit, the terminals, or ends, of all the resistors are connected to each other. This way, the electric current can flow through more than one path.

This structure is the one used in houses because even if one of the resistors does not work, it allows the others to keep working.

R1 Two resistors connected in parallel

R1

The total resistance of a group of resistors connected in parallel is calculated with this formula: 1 1 1 1 = + + ... + Rt R1 R2 Rn

R2

In cases of just two resistors, the formula is shortened to: R3

Rt =

Three resistors connected in parallel

Rn

R1 · R2 R1 + R2

You can also use the formula above for more than two resistors connected together. You just need to group the resistors in pairs until you get a single equivalent resistance.

In parallel circuits all the elements are connected to the same voltage: that of the generator. And the current provided by the generator is equal to the sum of* the currents that flow through each of the resistors.

R2

Measurement

R1

Explanation

Formula

Equivalent resistance

We calculate it as the inverse value of the sum of the inverse values of each of the resistors in the circuit. If there are two resistors, we can use the formula of the product of the two resistances divided by their sum.

1 1 1 1 = + + ... + Rt R1 R2 Rn

Voltage

All the elements connected to the battery will have the same voltage as the battery.

V = V1 = V2 = ... = Vn

Current

The current flowing through each branch of the circuit and will depend on the resistance value of the branch.

The total current, provided by the battery, is the sum of the currents flowing through the branches.

I = I1 + I2 + ... + In

n resistors connected in parallel

F ocu s on Eng lish The sum of something is the total amount of something. For example, the sum of 7 and 7 is 14.

Model example Calculate the equivalent resistance of the following connected resistors: 6 4 12

Solution: 1 1 1 1 1 1 1 3+2+1 6 = + + + + + = = Rt R1 R2 R3 4 6 12 12 12 To calculate the value of Rt, the result is inverted: Rt = 12 = 2 Ω 6

115

9 DIFFERENT CIRCUIT CONNECTIONS

Model example In the circuit in the diagram, calculate: a) the equivalent resistance. b) t he current provided by the battery. d) t he voltage drop in each resistor.

+ 12 V

3X

6X

c) the current flowing through each of the resistors.

Solution: Because these are two resistors in parallel, the equivalent resistance will be calculated using the following formula: R1 · R2 3·6 18 = = =2Ω Rt = R1 + R2 3+6 9 To calculate the current provided by the battery, we apply Ohm’s law: dividing the voltage by the equivalent resistance: I = V = 12 = 6 A Rt 2 Since the resistors are connected in parallel, both of them receive the same voltage.

V = V1 = V2 = 12 V All we need to do to calculate the current provided by the battery is apply Ohm’s law to each of the resistors: V V I1 = 1 = 12 = 4 A ; I2 = 2 = 12 = 2 A R1 3 R2 6

Understand, think, investigate...

15 Calculate the total resistance, the electric

16 Look at the circuits below with light bulbs (L)

current the battery provides and the current that circulates through each resistor, as well as the voltage of each light bulb in the following circuits. Imagine all the bulbs are the same and have the same resistance of 100 ohms.

and switches (S). The switches on each branch of the circuit can be closed or open. If they are closed, they allow the current to flow. If they are open, they stop the current flowing. Look at the position of the switches in each circuit, which bulbs will light up and which ones will not?

a)

100 X

100 X

L1

a)

+

100 X

10 V

S1

+V

L2

100 X L4

b)

S3

S2

b) 100 X

+

100 X

100 X

100 X

+

V

L1

S1

L2 L3

10 V S2

116

L3

L4

10 ENERGY SOURCES

Unit

5

Electrical energy is the source of energy that we humans use the most.

To generate it, we need to make use of the power found in primary energy sources. Alternatively, we can make use of meteorological phenomena such as sunlight or wind, and convert it into electrical energy in our power stations.

There are two categories of energy source:

Wind farms

➜➜ Primary energy sources: These include any form of energy available in the natural world before being converted or transformed. The light from the sun, wind, internal heat from the Earth, water, fossil fuels (coal, petroleum and natural gas), biomass and uranium are all examples of primary energy sources.

➜➜ Secondary energy source: This is the energy that comes from transforming a primary source. It is ready to be stored, transported and used in homes, industry, workplaces etc.

Wind farms are located in areas where there are strong and relatively constant winds. They are located on the coast, for example, where there is usually a continuous breeze or wind which can generate energy.

We can also classify energy sources based on if the energy is renewable or non-renewable. That is, if it comes from an unlimited source, or if it comes from a material which is in limited supply on our planet, such as oil or coal.

ää 10.1 Renewable energy By definition, renewable energy sources do not run out when we use them to generate the energy we want. In other words, they regenerate at a rate that is greater than or equal to the rate at which we consume them.

There are different types of renewable energy that we can use: solar energy, wind energy, geothermal energy, biomass or water energy.

Solar energy

Understand, think, investigate...

17 The mirror. Andalucía makes great use of solar energy, from solar energy plants to using photovoltaic energy and making use of solar panels to heat water for central heating or domestic hot water supply. Find out the similarities and differences between photovoltaic panels and solar energy panels, then explain them in your own words.

Solar energy is generated by the nuclear fusion reactions that take place in the Sun’s core. The energy released from the Sun reaches us through electromagnetic radiation in different forms: visible light, infrared radiation and ultraviolet radiation.

Solar energy can be used directly for lighting, natural heating, cooking in a solar oven, heating water for home use or central heating, or for other everyday tasks such as drying clothes. It is indirectly used when we use it to generate electrical energy.

Wind energy Wind energy is the energy found in moving air mass. In reality, it comes from the Sun, as the irregular heating of air mass is what causes the differences in pressure that cause them to move.

Modern wind turbines, or windmills, installed in parks or wind farms transform the movement of air mass, or wind, into electrical energy. The energy from the wind is also used directly in sailboats and hang gliders.

It was also widely used in windmills and for milling grain or extracting water, but this is not so common these days.

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10 ENERGY SOURCES

Geothermal energy Geothermal energy comes from the internal heat in the Earth. It is used indirectly to generate electrical energy and directly for central heating systems and heating water for domestic use.

Energy from biomass This is the energy obtained from any organic material, plants or animals, as well as products that have been naturally or artificially transformed by them. We make use of biomass by burning waste in order to obtain electrical energy and heat energy, or though processes that allow other fuels to be obtained, for example, biodiesel.

Wave power station

Hydraulic energy The energy contained in water, called hydraulic energy, manifests in different ways. The moving water in rivers, marine currents, waves and tides is kinetic energy, whereas the energy from water stored in a dam is potential energy.

Hydraulic energy is used directly to transport people and goods downstream, as well as to move waterwheels that supply water. It is indirectly used in:

➜➜ Hydroelectric power stations. In this type of power station, the mechanical energy of the water that flows through a river and the water stored in a dam is used to produce electrical energy.

There is no fixed model of a wave power station, they can be quite different. Recently, a power station started using buoys fixed to mechanical arms which are moved by the waves.

➜➜ Tidal power stations. The difference in height between high tide and low tide means we can use the energy from the motion of large masses of water to obtain electricity.

➜➜ Wave power stations. These use the energy from wave motion, which comes from the effect of wind on the seas or oceans, to generate electricity.

Hydroelectric power station

Tidal power station Power grid Water stored during high tide

Transformer

Intake channel

Low tide

Generator

Transformer

Turbine

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ää 10.2. Non-renewable energy Non-renewable energy sources are those that run out as they are used. This could be because they do not regenerate, or because they do so at a slower rate than they are consumed. The most commonly-used non-renewable energy sources are coal, petroleum, natural gas and nuclear fuel.

Coal Coal is a fossil fuel that is formed from decomposed plants that accumulated in swampy or marine areas millions of years ago. It is mainly made up of carbon, hydrogen and oxygen. Coal is generally used to produce electrical energy, but it is also used in industrial processes such as producing steel.

Petroleum Petroleum is a heterogenous mixture of organic compounds, basically hydrocarbons, which are insoluble in water. It comes from the sedimentation of zooplankton and algae on seafloors over millions of years which is subjected to intense heat and pressure.

Petroleum is the main source of energy in developed countries. It is transformed into fuels that can be used both for transportation and for producing electrical energy. Other products, such as plastics and asphalt for roads, are also obtained from petroleum.

Natural gas Natural gas is a heterogeneous mixture of organic compounds, mainly hydrocarbons, in a gaseous state. Pockets of this natural gas are often found above oil deposits. This fossil fuel pollutes the least when compared to others and its transformation from the oil deposit to where it is used is minimal. Natural gas is used to generate electrical energy or for domestic use such as central heating or in cooking.

Nuclear fuels The most commonly used element in nuclear energy production is uranium.

Energy is obtained from nuclear fission, which is when the atoms of the uranium-235 isotope are broken. When a uranium atom undergoes fission by being bombarded by a neutron, two lighter atoms are obtained. The final mass is less than the sum of the initial masses. Just like in the fusion reaction, that difference in mass is transformed into energy. The reaction must be controlled, as when a uranium atom is broken, neutrons are released that then break other nearby uranium atoms, releasing larger amounts of energy. This process is called a chain reaction.

The energy released is mainly used to produce electrical energy, although it has also been used for destructive purposes in nuclear weapons.

Nuclear fission Neutron

Heavy nucleus

The nucleus decomposes into other smaller ones

Energy is released as well as neutrons that hit other heavy nuclei

Nuclear fission occurs when a nucleus is bombarded by neutrons and breaks.

The nucleus breaks down into two fragments and a few neutrons that can then break more nuclei, producing a chain reaction. A moderator material is used to control and slow down these neutrons.

119

11 HOW ELECTRICAL ENERGY IS GENERATED AND TRANSPORTED

Stator coils Rotor magnets

N

N

The electric current that reaches our homes is generated in power stations, and most of these have turbines and alternators. There are different kinds of power station which use different energy sources to move the turbine.

In thermal power stations, the energy comes from the heat generated when burning coal, natural gas, wood or any other type of fuel.

Generating electrical energy

S

ää 11.1 Producing electricity. Power stations

Drive shaft

S Alternating current

In nuclear thermal power stations, the energy needed to generate the steam to move the turbine comes from controlled nuclear fission reactions.

In solar thermal power stations, the heat from the sun is used to generate the steam which moves the turbine.

ää 11.2 Alternators Alternators are machines that turn mechanical energy into electrical energy. The energy that causes the movement of an alternator can come from:

➜➜ steam, generated using water at a high temperature and pressure This alternator is made up of a rotor with permanent magnets and a stator with four coils.

As the rotor turns, or rotates, it produces constant changes in the magnetic fields that the coils are subjected to. This generates (induces) an alternating current. This current is then transmitted through its terminals to a transformer.

in a nuclear or thermal power station.

➜➜ water falling in a hydroelectric station. ➜➜ wind or waves.

Generators have a fixed part known as the stator, and a mobile part called a rotor. In the alternator in the diagram, the stator is made up of coils of conductive wire, and the rotor is a set of magnets.

They produce energy thanks to electromagnetism. Moving magnets generate variable magnetic fields which create an induced electric current in a conducting wire.

Nuclear power station Power grid

Primary circuit Secondary circuit Cooling circuit Containment building

Reaction engine

Transformer Steam generator Control rods

Turbines Steam Cooling tower

Generator

Water

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ää 11.3 Power transmission lines

F ocu s on Eng lish

Electricity must be transported from where it is generated to where it is used, in industrial plants, homes and street lighting etc. Electricity must be generated at the same rate* as it is used, as it is not possible to store it in large amounts.

rate: the speed at which something happens in a period of time

Not all transmission lines have the same voltage. So they are sorted into lines with low, medium and high tension.

ää 11.4 Substations Electrical energy is generated at a voltage of between 5 and 25 kV (medium voltage), and must be increased to between 222 kV and 400 kV (high voltage) to reduce the loss while being transported. After transporting the electrical energy, the voltage goes down again to 690 V for it to be used in industry, and to 230 V in homes.

Transformers change the voltage, and these machines are found in places called substations.

Transformer.

Transformation and transport of the electric current Generation (Medium voltage: 5-25 kV)

Transport (High voltage: 220-400 kV)

Substation Transmision lines (69 kV)

Distribution lines (12 kV) Industry

Consumption (Low voltage) 690 V Homes 220-230 V

Distribution centre

Understand, think, investigate...

18 Look up the Joule effect and the problems that come from transporting electricity across long distances. Why is it important to transport electrical energy at high tension?

19 In some countries, people that live close to electrical energy transportation lines economically compensated. Find out why.

are

121

12 ENERGY EFFICIENCY

ää 12.1 Labels and energy efficiency Energy efficiency is the relationship between the energy we supply to a system and the useful energy we really get.

Efficiency =

Useful Energy Energy supplied

A device is energy efficient if it has a high energy performance. This means that the device uses most of the energy supplied, and wastes or loses little energy.

Because saving energy and reducing carbon dioxide emissions is very important, the European Parliament requires all electrical appliances have an energy label showing their level of energy efficiency.

Refrigerators, freezers, washing machines, dishwashers, dryers, washer dryers, light sources, electric ovens, air conditioning units, kitchen extractor fans, water heaters, vacuum cleaners, televisions and even tyres must have these energy labels.

Using energy-efficient electrical appliances means we save energy and water in our homes. This way we are contributing to a more efficient use of energy and natural resources.

ää 12.2 Energy labels The energy label looks like the one in the diagram on the opposite page. The following fields are highlighted:

➜➜ The brand and model. The name of the manufacturer and the model of the electrical appliance.

➜➜ Energy efficiency of the product. This is the most important part of the label. It shows the energy consumption category of the appliance. It relates it to the average consumption of electrical appliances of the same type. The highest category is the lowest energy consumption, and vice versa.

➜➜ Annual electricity consumption expressed in kWh and calculated based on standard conditions of use.

➜➜ Other characteristics according to the type of electrical appliance.

For example, a washing machine shows its annual electricity consumption, and its energy class, as well as the number of litres of water per cycle, the amount of clothing that can be washed, and the noise made during the wash and spin cycles.

➜➜ QR code. On devices with modern labels, a QR code provides access to the description of the model in the European Union registry database.

C RE AT E

English

Make an information poster about energy efficiency and how to understand energy labels.

122

Unit

5

The energy label UNDERSTANDING THE LABELS Using an average class G refrigerator as a reference Brand and model

Energy efficiency of the product

Annual electrical consumption

The most efficient appliances

Medium consumption

High energy consumption Other characteristics of this type of electrical appliance

A

Less than 20 %

B

Between 20 % and 30 %

C

Between 30 % and 40 %

D

Between 40 % and 50 %

E

Between 50 % and 70 %

F

Between 70 % and 85 %

G

Between 85 % and 100 %

Understand, think, investigate...

20

4-person solution. Compare the old and

new energy efficiency label of the products.

Which advantages and disadvantages do you think each one has?

21 The sizes of televisions are usually shown in inches.

Do you know which system of measurement this unit belongs to? How many centimetres are there in an inch?

22

Find out the meaning of the following

pictograms and say which type of electrical household appliances which you could find them on:

123

kshop

or TECHNOLOGY w

Electrical measurements Project presentation

We can use a circuit diagram to calculate electrical measurements such as electric current and voltage. In this project you will assemble a circuit and check your calculations by using a multimeter.

study the circuit

We are going to assemble a parallel circuit. To make the circuit, we are going to need a 3 Volt battery which we will connect to a 220 Ohm resistor, and a 1 000 Ohm resistor. The structure of the circuit will match the one shown in the diagram. First, we will use this diagram to calculate electric current and voltage in all the circuit parts.

It

3V

3V

+

Try to solve the circuit yourself and compare your results with the ones provided in the table of solutions. The details of the problem are in black, and the values calculated from them are shown in red.

I2 I1

+

0,22 kX

Component

Voltage [V]

Electric current [mA]

Battery

3

16.63

R1

3

13.63

0.22

R2

3

3

1

1 kX

Req

Resistance [KΩ]

Notice how a space has been left blank in the field for the resistance of the battery. This resistance does not exist, but the value of the equivalent resistance (Req), can be calculated instead.

To check if the results are correct, you can calculate the value of the equivalent resistance by using two methods shown here:

• Method A: Calculate the equivalent resistance by connecting resistors in parallel.

R Ò R2 Req = 1 = R1 + R2

1 Ò 0.22 1 + 0.22

= 0.18 KΩ = 180 Ω

• Method B: Calculate the equivalent resistance by applying Ohm’s law. In this case, we know the voltage of the battery and the current it produces, therefore: 3V Req = V = = 0.18 KΩ = 180 Ω 1 16.63 mA

ASSEMBLING the circuit

To assemble the circuit, you are going to need:

• 1 breadboard.

• A 1 kΩ resistor, and a 220 Ω resistor • A 3 volt battery mounted on the circuit using two AA 1.5 volt batteries • A digital multimeter

124

Unit

5

First measurement: Equivalent resistance It is important NOT to connect the batteries to the circuit when measuring the equivalent resistance. Follow the steps:

1 Copy the circuit on the left. The multimeter is connected in parallel to the two resistors.

2 Move the dial to point to the Ω symbol.

3 Write the value that appears on the screen.

Second measurement: Total electric current in the circuit Follow the steps to measure the electric current:

1 Connect the battery where you connected the multimeter.

2 Connect the multimeter as shown in the picture, so you can measure the electric current for the whole circuit. The red cables are connected to the points with the highest voltage in the circuit.

3 Move the dial to point to the mA symbol.

4 Write the value that appears on the screen.

Check results and analyse errors We are going to use absolute error and relative error.

Absolute error is the difference between the value we calculated and the value we measured. If we calculated a resistance of 3.2 Ω and then the measurement was 3.1 Ω, the absolute error is: Ea = 3.2 – 3.1 = 0.1 Ω Relative error is the percentage of error.

1 Divide the absolute error by the calculated value.

2 Multiply the answer by one hundred to get the percentage.

In the previous example, the relative error would be: Er =

0.1 ohm 3.2 ohm

Ò 100 = 3.13 %

Copy this table including your values and errors.

Measurement

Calculated value

Equivalent resistance

180 ohm

Intensity through the circuit

16.63 mA

Measured value

Absolute error

Relative error

Are your relative error percentages low? Do you think your values can be considered correct?

125

aterial the work m r to choose be em m .

Re rtfolio for your po in this unit

CTISE

REVIEW AND PRA

13 A buzzer is connected to a 4.5 V battery and an

Electric current and electric circuits 1 In your own words, describe what an electric current is.

2 What is an electric circuit? Which parts does it have? Which of the parts are essential for it to be an electric circuit?

3 What is an atom? What elements does it have?

14 A 100 Ω bulb is connected to a 9 V battery. Draw the electric circuit using the appropriate symbols and calculate the electric current that circulates through the bulb.

15 Imagine an electric motor with a resistance of 36 Ω

Electric circuit parts 4 Name a characteristic of each type of generator.

5

electric current of 0.05 A is measured through it. Draw the electric circuit using the appropriate symbols and calculate the resistance of the buzzer.

Explain what voltage is in your own words.

What relationship is there between voltage, energy and electric charge?

6 How are materials classified according to whether they allow an electric current to flow or not? Write three examples of each.

with an electric current of 0.5 A circulating through it. Draw the electric circuit using the appropriate symbols and calculate the voltage of the battery that is connected to the motor.

Resistors in a circuit 16 Calculate the total resistance of the following groups of resistors:

7 Draw a table in your notebook to classify the

12 W

different loads you have studied. Include the energy transformations each of them makes.

Group 1

28 W

40 W

8 What difference is there between a button, a switch and a multiway switch? Draw their symbols.

30 X

9 From memory, draw at least six symbols for electrical devices used in circuit diagrams.

Group 2

25 X 30 X

Electrical resistance 10 Think about a basic circuit with a generator and an electric resistor connected with conductors. What do we mean when we say: “the more voltage the generator has, the more current will flow round it”? Is it linked to Ohm’s law?

11 Copy and complete the following table of the basic electric magnitudes with their initials, units and symbols.

Quantity

Initial

Unit

Symbol

Voltage

Ampere R

12 Copy the table and apply Ohm’s law to complete it.

Voltage (V)

Electric current (A)

Resistence Z

33

11

150

75 2.5

126

20

17 Are the following groups of resistors connected in series or in parallel? Calculate their total resistance.

Circuit 1 R1 = 5 X R2 = 3 X

Circuit 2 R1 = 12 X R2 = 13 X

R1 = 5 X

R1 = 12 X

R2 = 3 X

R2 = 13 X

R3 = 4 X

R3 = 25 X

R3 = 4 X R1 = 6 X Circuit 3

R3 = 25 X Circuit R2 =42 k X

R =6 4X X R21 =

R2 = 2 k X

RR32==2,4 4 XX

R1 = 1 k X

R3 = 2,4 X

R1 = 1 k X

R3 = 5 k X R3 = 5 k X

In anayaeducacion.es In the resource bank you will find documents that explain how to use the techniques or keys indicated in some activities.

Unit

18 Write the steps for solving a parallel circuit and a

29

Intuition and deduction.

There are

refrigerators on the market nowadays with touch screens, Wi-Fi and other technological advances.

What do you think these innovations are used for?

series circuit. Use two 15 kΩ and 5 kΩ resistors and a 5 V battery in both circuits.

19 In your notebook, draw a comparative table to show the characteristics of series and parallel circuits. Include their total resistance, current and voltage.

20 You learnt that to calculate the total resistance of two resistors in parallel, the inverse operation of the sum of inverse value has to be applied.

You have also learnt that you get the same value if you divide the product by the sum of both.

Demonstrate this mathematically.

30 What kitchen appliances do you know that work with a source of energy that is not electrical energy?

What are their advantages and disadvantages?

31

means? Has a fuse blown in your house before?

What is the reason for this phenomenon? Ask for help at home to identify the power used on an electricity bill and explain what the bill shows.

two are connected in series and another two are connected in parallel. Which pair of bulbs will light up more? Support your answer.

33

22

Effect and reach. Make a table listing the

advantages and disadvantages of using electrical energy. Draw two columns, with the advantages in the right column, and the disadvantages in the left column.

23 What physical principle is the operation of an

save water, heating and gas.

35 Classify the ways of saving the resources that you agreed on in the previous activities according to how difficult they are to do. Could you commit to doing at least five of them?

24 List at least three elements used in electrical 25 Which device increases the value of the generated

36 Make a list of the electrical appliances you have at home. Try to find the electrical power they use in kilowatts (kW) on their technical data plate or on the Internet. Ask someone at home how many hours you think the electrical appliances are switched on every day. Multiply the power of each electrical appliance by the hours they are used.

Add all the values you got and compare the figure with your classmates. See who uses the most and the least amount of electricity.

voltage so it can be transported?

Using electricity in our homes 26 What electrical household appliances must show the energy efficiency label by law?

27 Make a list of the most important information that an energy efficiency label must have. Can you think of any other important information that could be included?

Think of ways to reduce the use of electricity

in your home, and in your school. Work in groups to make a list of steps to save electricity and share them with the rest of your class.

34 Now, repeat activity 33 but thinking of ways to

alternator based on? energy distribution lines.

There are refrigerators that do not work using electrical energy. Search for information on them and make a voice recording or video of yourself explaining how they work.

32 What do you think the expression to blow a fuse

21 There are four identical light bulbs in a circuit,

Electrical energy

5

37 Watch the documentary “The E-waste tragedy”

28

Timeline. Search for information on the

different technologies used in the production of electronic televisions since they appeared in 1936. Order them on a timeline. You can make the timeline visual with pictures or photos.

Remember to check out the Learn by playing and Study: Mind Map activities available at anayaeducacion.es.

by Documentos TV on the Internet. It is about the illegal trafficking of electronic waste. Who is responsible for it? Who is benefiting from it and who is harmed by this trafficking? Which steps could you take as a consumer to help prevent this?

Talk about this with your classmates.

127

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