Light and Lighting

Light and Lighting An inquiry-based unit for primary and elementary students in an after-school setting. The unit provides background information and hands-on activities on the energy of light and lighting.

Grade Levels:

Pri

Primary

Elem

Elementary

Subject Areas: Science

Social Studies

Language Arts

Math

Technology

NEED Mission Statement The mission of The NEED Project is to promote an energy conscious and educated society by creating effective networks of students, educators, business, government and community leaders to design and deliver objective, multisided energy education programs.

Teacher Advisory Board

Permission to Copy

Constance Beatty Kankakee, IL

Barbara Lazar Albuquerque, NM

James M. Brown Saratoga Springs, NY

Robert Lazar Albuquerque, NM

NEED curriculum is available for reproduction by classroom teachers only. NEED curriculum may only be reproduced for use outside the classroom setting when express written permission is obtained in advance from The NEED Project.

Permission for use can be obtained by contacting info@need.org.

Mark Case Randleman, NC

Leslie Lively Porters Falls, WV

Teacher Advisory Board

Amy Constant - Schott Raleigh, NC

Melissa McDonald Gaithersburg, MD

Nina Corley Galveston, TX

Nicole McGill Washington, DC

Samantha Danielli Vienna, VA

Hallie Mills St. Peters, MO

Shannon Donovan Greene, RI

Jennifer Mitchell Winterbottom Pottstown, PA

Nijma Esad Washington, DC Linda Fonner New Martinsville, WV Teresa Fulk Browns Summit, NC Michelle Garlick Long Grove, IL Erin Gockel Farmington, NM Robert Griegoliet Naperville, IL Bob Hodash DaNel Hogan Tucson, AZ

Mollie Mukhamedov Port St. Lucie, FL

In support of NEED, the national Teacher Advisory Board (TAB) is dedicated to developing and promoting standardsbased energy curriculum and training.

Energy Data Used in NEED Materials NEED believes in providing teachers and students with the most recently reported, available, and accurate energy data.

Most statistics and data contained within this guide are derived from the U.S. Energy Information Administration.

Data is compiled and updated annually where available.

Where annual updates are not available, the most current, complete data year available at the time of updates is accessed and printed in NEED materials. To further research energy data, visit the EIA website at www.eia.gov.

Cori Nelson Winfield, IL Don Pruett Jr. Puyallup, WA Judy Reeves Lake Charles, LA Tom Spencer Chesapeake, VA Jennifer Trochez MacLean Los Angeles, CA Wayne Yonkelowitz Fayetteville, WV

1.800.875.5029 www.NEED.org Š 2019

Greg Holman Paradise, CA

Printed on Recycled Paper

2

Š 2019

The NEED Project

Light and Lighting

www.NEED.org

Light and Lighting

Table of Contents Standards Correlation Information

4

Making Shadows

32

Materials 5

Where is the Sun?

33

Teacher Guide

Hand Shadows

34

6

Answer Key

12

Spectroscope 35

Lab Safety Rules

14

Reflection 36

Student Informational Text

15

Maze 1

37

Thermometer 21

Maze 2

38

Solar Energy to Heat

22

Photovoltaic Cells Explanation

39

Solar Balloon

23

Solar House

40

Radiometer 24

Comparing Light Bulbs

41

Radiometer Explanation

25

Facts of Light

42

Glow Sticks

26

Home Energy Use Survey

44

NaturePrint® Paper

27

Light and Lighting Survey

45

UV Beads

30

Evaluation Form

47

How Light Travels

31

Originally developed in partnership with the U.S. Department of Energy, National Association of Public and Land-Grant Universities, and the National 4-H Council’s 4-H Afterschool program.

© 2019

The NEED Project

Light and Lighting

www.NEED.org

3

Standards Correlation Information www.NEED.org/curriculumcorrelations

Next Generation Science Standards This guide effectively supports many Next Generation Science Standards. This material can satisfy performance expectations, science and engineering practices, disciplinary core ideas, and cross cutting concepts within your required curriculum. For more details on these correlations, please visit NEED’s curriculum correlations website.

Common Core State Standards This guide has been correlated to the Common Core State Standards in both language arts and mathematics. These correlations are broken down by grade level and guide title, and can be downloaded as a spreadsheet from the NEED curriculum correlations website.

Individual State Science Standards This guide has been correlated to each state’s individual science standards. These correlations are broken down by grade level and guide title, and can be downloaded as a spreadsheet from the NEED website.

4

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Materials ACTIVITY

MATERIALS IN KIT

MATERIALS NEEDED

Light to Heat—Using Thermometers

Demonstration

thermometer Student

thermometers

Black

and white construction paper Scissors

Colored

pencils Black

and white paints (optional)

Light to Heat—Solar Balloon and Radiometer

Solar

balloon Radiometer

Colored

pencils

Light and Chemical Changes—Glow Sticks and NaturePrint® Paper

10 Glow sticks NaturePrint®

Paper

Ice water Warm

water Scissors

Paper

Cups

Stored Light and Colors—UV Beads

UV beads Pipe

cleaners

Sunscreen

(spray) Resealable

plastic bag

Light Travels and Making Shadows

Flashlights

Clay

Pieces

of cardboad Sharp

pencils Crayons

Rulers

Scissors

Light Can Be Separated

Spectroscopes

Flashlights

Spray

bottles

Colored

pencils or crayons Water

Light Can Be Reflected

Flashlights

Mirrors

Yarn

Light Can Be Turned Into Electricity

PV cell kit Clay

Sharp

pencils Shoe

boxes Scissors

Crayons

It Takes Energy to Make Light

Incandescent

light bulb Compact

fluorescent light bulb LED

bulb

Calculators

Lamp

Thermometers

We Can Save Energy—Home Energy Survey

Paper

Pencils

Kit materials are available for purchase by contacting NEED at 1-800-875-5029.

Light and Lighting Kit 1 Leader guide 1 Demonstration thermometer 1 Radiometer 5 Spectroscopes 1 Incandescent halogen bulb 1 Compact fluorescent bulb 1 LED bulb

© 2019

The NEED Project

Light and Lighting

1 PV Cell Kit (with solar panel, fan & Motor) 1 Solar balloon 1 Pack of NaturePrint® Paper 1 Pack of UV beads 1 Pack of pipe cleaners 5 Flashlights

www.NEED.org

5 Spray bottles 5 Flat mirrors 10 Student thermometers 20 Glow sticks 1 Package clay

5

Teacher Guide Grade Levels

Unit Preparation

Primary,

grades K-2

Read

the guide and become familiar with the information, activities, and equipment in the kit.

Elementary,

grades 3-5

Gather

the materials needed for activities using the chart on page 5.

 Time Approximately

10-12 one-hour sessions

Practice

the experiments to gain an understanding of possible outcomes, difficulties, and questions.

Make

copies of student worksheets and the informational text, as needed.

Prepare

digital copies of masters for projection and discussion.

Make

two copies of Light and Lighting Survey on page 45 for each student. One copy can be used as a pre-assessment, the other, a post-assessment of student understanding.

Allow

the students to take their work home each day to share with their families.

With

all of the activities, give older students responsibility for working with the younger students to help them understand and complete the experiments and student worksheets.

Make

sure the students understand the applicable Lab Safety Rules on page 14.

Activity 1: Light to Heat—Using Thermometers  Objective Students

will be able to describe how different colors absorb energy from the sun.

 Concepts Light

is radiant energy that travels in waves.

Light

waves can be refracted, reflected, and absorbed by substances.

When

light is absorbed by substances, it is often transformed into thermal energy (heat).

We can measure heat with a thermometer.

 Materials Demonstration

and student thermometers Black

and white paper Scissors

Colored

pencils

Black

and white paint (optional) Thermometer

worksheet, page 21 Solar

Energy to Heat worksheet, page 22

Procedure 1. Set up five centers, each with black and white paper, scissors, colored pencils, and two student thermometers.

2. Introduce the activity using the pertinent information in the informational text (pages 15-20).

3. Use the demonstration thermometer to show the students how to read a thermometer, explaining the two scales—Fahrenheit and Celsius.

4. Have the students complete the Thermometer and Solar Energy to Heat activities.

5. Discuss the students’ answers to the Conclusion questions.

Extension Have each student paint one hand with black paint and the other with white paint and hold their hands in the sun for a few moments. Have them observe the difference in temperature and explain why one hand feels hotter than the other.

6

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Activity 2: Light to Heat—Solar Balloon and Radiometer  Objectives

Students

will be able to explain how light transforms to heat, and provide an example.

Students

will be able to describe how a radiometer works.

 Concepts Light

waves can be refracted, reflected, and absorbed by substances.

When

light is absorbed by substances, it is often transformed into thermal energy (heat).

When

substances absorb light and turn it into heat, they usually expand.

 Materials Procedure Solar

Balloon worksheet, page 23 Radiometer

worksheet, page 24 Radiometer

Explanation, page 25

Solar

balloon Radiometer

Colored

pencils

1. Introduce the activity by reminding students that black objects absorb light energy and white objects reflect light energy.

2. Go outside to fly the solar balloon on a sunny day, using the directions on page 23.

3. Demonstrate the radiometer by putting it in the sun (or in a bright light) and letting the students observe and complete the Radiometer activity.

4. Discuss the students’ answers to the Conclusion and Explanation questions.

5. Demonstrate or display the Radiometer Explanation to further understanding of how the radiometer works.

Activity 3: Light and Chemical Changes—Glow Sticks and NaturePrint® Paper  Objective Students

will be able to describe chemical reactions involving light and heat.

 Concepts Light

can produce chemical changes in substances.

Chemical

reactions can produce light.

Adding

thermal energy (heat) can speed up chemical reactions; removing thermal energy (cooling) can slow them down.

 Materials 10 Glow sticks 5 Cups of ice water 5 Cups warm water NaturePrint®

Paper

Scissors

Paper

Glow

Sticks worksheet, page 26 NaturePrint®

Paper worksheets, pages 27-29

Procedure 1. Set up five centers, each with one cup each of ice water and warm water and two glow sticks.

2. Introduce the activity to the students, explaining that chemical reactions can produce light and that light can cause chemical changes.

3. Divide the students into five groups, have them go to the centers. Give each student a copy of the activity sheets.

4. Instruct the students to examine the glow sticks and then break the glow sticks and shake them. Instruct students to put one in the cup of ice water and one in the cup of warm water, and observe the amount of light produced. Discuss. You can put the glow sticks in a freezer to save if you like; the cold will slow the chemical reaction. © 2019

The NEED Project

Light and Lighting

www.NEED.org

7

5. Have each student cut out a sun template or create his/her own design to use with the NaturePrint® Paper. Students can also use their own items to place on top.

6. Give each student a piece of the NaturePrint® Paper and follow the directions on the worksheet and the package to make the prints.

Allow the students to take their finished projects home.

7. Discuss the students’ answers to the Conclusion and Extension questions.

Activity 4: Stored Light and Colors—UV Beads  Objective Students

will be able to explain how light is stored and released in some objects.

 Concepts Light

can produce chemical changes in substances.

Some

substances can store light and release it as light at a later time.

 Materials UV beads Pipe

cleaners Sunscreen

(spray)

Resealable

plastic bag UV Beads worksheet, page 30

Procedure 1. Set up five centers, each with paper, scissors, and tape.

2. Introduce the activity to the class, distributing the worksheet.

3. Distribute five beads and one pipe cleaner to each student. Instruct the students to string their beads onto the pipe cleaners and make bracelets.

4. Place several beads into the plastic bag. Show students the bag and then spray both sides of the bag with liberal amounts of sunscreen.

5. Take students outside to conduct the experiment. Have students observe the bag of beads and note differences in the beads compared to their bracelet. Discuss.

6. Allow the students to take their bracelets home.

7. Discuss the students’ answers to the Conclusion and Extension questions.

Activity 5: Light Travels and Making Shadows  Objectives Students

will be able to describe how light travels.

Students

will be able to explain how shadows are created.

 Concepts Light

waves travel in a straight line.

A shadow is an area where an object is blocking the light.

The

size of a shadow changes according to the direction and angle of the light source.

8

© 2019

The NEED Project

Light and Lighting

www.NEED.org

 Materials Flashlights

Pieces

of cardboard Sharp

pencils Clay

Crayons

Rulers

Scissors

How

Light Travels worksheet, page 31 Making

Shadows worksheet, page 32 Where

is the Sun? worksheet, page 33 Hand

Shadows handout, page 34

Procedure 1. Set up five centers, each with a flashlight, a sharp pencil, a new crayon, and a piece of clay.

2. Place the students at the centers, distribute worksheets, and introduce the activity.

3. Instruct the students to complete the How Light Travels activity. Discuss the Conclusion questions.

4. Take the students outside to observe shadows.

5. Instruct the students to complete the Making Shadows and the Where is the Sun? activities. If time allows, have students create the hand shadows on page 34.

6. Discuss the students’ answers to the Conclusion and Extension questions.

7. Allow the students to take page 34 home to complete with their families.

Activity 6: Light Can Be Separated  Objective Students

will be able to describe visible light and how we can separate it into colors.

 Concepts Visible

light is made of many wavelengths of radiant energy.

Visible

light can be separated into different colors of light according to their wavelengths.

 Materials Spectroscopes

Flashlights

Colored

pencils or crayons Spray

bottles with water Spectroscope

worksheet, page 35

Procedure 1. Introduce the activity with a discussion of rainbows.

2. Distribute the Spectroscope worksheet to the students.

3. Allow each student to look through a spectroscope and instruct the students to draw the colors they see on their worksheets.

4. Go outside in the sun and use the spray bottles to make rainbows.

5. Discuss the students’ answers to the Conclusion and Extension questions.

© 2019

The NEED Project

Light and Lighting www.NEED.org

9

Activity 7: Light Can Be Reflected  Objective Students

will be able to describe the reflection of light.

 Concepts Light

travels in a straight line.

Light

waves can be reflected.

The

angle of incidence of light is equal to the angle of reflection.

 Materials Flashlights

Mirrors

Yarn

Reflection

and Maze worksheets, pages 36-38

Procedure 1. Introduce the activities to the students with a discussion about mirrors and other materials that reflect light. Distribute the Reflection activity.

2. Have the students choose partners or groups and conduct the experiment.

3. Discuss the students’ answers to the Conclusion questions.

4. Distribute the mazes. Have the students complete Maze 1 and take Maze 2 home to complete with their families.

Activity 8: Light Can Be Turned Into Electricity  Objective Students

will be able to investigate a PV cell, and describe how it transforms energy.

 Concepts A PV cell can convert light into electricity.

Electricity

can be used to perform work.

 Materials PV cell kit Sharp

pencils Clay

5 Shoe boxes

Scissors

Crayons

Photovoltaic

Cells Explanation, page 39 Solar

House worksheet, page 40

Procedure 1. Set up five centers with shoe boxes, scissors, crayons, and pencils.

2. Introduce the activity by discussing PV cells, how they work, and where people see them.

3. Distribute the Solar House activity. Have the students go to the centers and make houses out of the cardboard boxes by adding windows and doors. Take the houses outside on a sunny day.

4. Install the PV cell with the fan on each house in turn to show how a PV cell turns light into electricity.

5. Discuss places where PV cells would be very helpful, such as in rural or remote areas without access to the electricity grid, and on road signs. Use or project the Photovoltaic Cells Explanation to futher student understanding of how a PV cell works.

10

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Activity 9: It Takes Energy To Make Light  Objective Students

will be able to compare types of bulbs and describe their heat output.

 Concepts Some

light bulbs produce more heat than others.

Some

light bulbs are more energy efficient than others.

Life

cycle cost is the total cost of using an appliance and is more important than purchase price.

 Materials Lamp

Incandescent

light bulb CFL

bulb LED

bulb

Calculators

Comparing

Light Bulbs worksheet, page 41 Facts

of Light worksheets, pages 42-43

Procedure 1. Set up the lamp so that it is convenient to all of the students.

2. Distribute pages 41-43 and introduce the activity by talking about lighting, how many light bulbs are in the students’ homes, and how many use compact fluorescent light bulbs at home. Emphasize that they must pay for the electricity to operate lights.

3. Conduct the comparison activity according to the directions on page 41, allowing all of the students to observe.

4. Have the students read the Facts of Light individually or as a class. Complete the Facts of Light activity as a group. Discuss reasons why people have been slow to use CFL and LED bulbs—the initial cost of the bulbs, limited understanding of life cycle costs, buying habits, not enough information.

5. Make sure the students take their worksheets home to discuss with their families.

Activity 10: We Can Save Energy—Home Energy Survey  Objective Students

will be able to identify ways they could save energy in their daily activities and lifestyle.

 Concepts We use energy in many ways to make our lives more comfortable and efficient.

There

are many ways we waste energy.

Using

energy costs money.

There

is not an infinite amount of usable energy.

We need to conserve energy whenever we can.

 Materials Home

Energy Survey, page 44

Paper

Pencils

Procedure 1. Ask students to brainstorm ways they use and waste energy at home.

2. Have the students brainstorm a list of ways that they could save energy at home.

3. Distribute the survey and discuss their predictions.

4. Have the students take the survey home to complete with their families. Have a discussion with students about their results.

 Evaluation Distribute

Light and Lighting Survey to students as a post-assessment.

If you have young students, you can read the questions to them. Collect the forms. Share the results with NEED, if you like!

Together

with the students, complete the Evaluation Form on page 47 and return it to NEED. © 2019

The NEED Project

Light and Lighting www.NEED.org

11

Answer Key Thermometer, page 21 Water

Boils—212°F, 100°C Human

Body—98.6°F, 37°C Water

freezes—32°F, 0°C

Solar Energy to Heat Worksheet, page 22 Which color absorbed the most energy? What evidence from the activity shows you this? Black should absorb the most energy. Students should find that the black covered thermometer got warmer.

How should this information affect your clothing choices? What color will you wear on a sunny day? Student answers should reflect that wearing dark colors during summer might make them hotter.

Which will be hotter on a sunny day, a car with a dark interior, or a car with a light tan interior? How do you know? Student answers should reflect that a car with lighter interior will be less hot.

Solar Balloon, page 23 Explain what happened to the air inside the balloon and why it rose? The air in the balloon was heated because the balloon is black and absorbed the light from the sun and changed it to heat. Warm air rises and the air inside the balloon became warmer than the air around it causing it to rise.

Will the balloon fly on a sunny but very cold winter day? Yes the balloon will fly on a sunny but cold day.

Radiometer, page 24 Explain how the radiometer turns the sun’s energy into motion. Light energy from the sun enters the radiometer, the light energy is changed to heat. The black side of the vane absorbs more of this energy and heats up the air in the radiometer. The air molecules then speed up and begin bouncing off of the radiometer vanes. The white sections don’t rebound as much of the air molecules because they reflect more energy. The black side rebounds more of the air molecules because it’s warmer. One side is pushing the energy more than the other, causing the radiometer to spin.

Glow Sticks, page 26 Explain how heat affects the chemical reaction in a glow stick. Student answers should reflect that the glow stick glows more brightly in the hot water, and in the cold water its light is dimmed. Additional heat speeds up the chemical reaction in a glow stick causing more light to be produced, while removing heat slows it down.

NaturePrint® Paper, page 27 Describe how your NaturePrint® Paper changed over time. Explain why you think this occurred. The paper, when placed in the light, goes through a chemical reaction causing it to change colors. Students should say that their papers had designs imprinted or left behind. The areas shaded by objects did not change colors, while the surrounding areas did.

UV Beads, page 30 What happened to your beads outside in the sun? The sun should cause the beads to change color because the beads undergo a chemical reaction when exposed to UV radiation.

How does sunscreen affect the UV beads? The beads change color, like your skin, when exposed to UV rays. If sunscreen is applied, less UV radiation gets through, causing less of a color change.

How Light Travels, page 31 How does light travel? Light travels in a straight line, but is capable of spreading out. Light waves can be absorbed, reflected, or refracted.

Making Shadows, page 32 What variables affect the size and shape of an object’s shadow? Possible student answers could include: how far away the light is from the object, the type of light, the shape of the object, the angle of the light or the object, the size of the object, etc.

12

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Where is the Sun?, page 33 Cactus

1: overhead Cactus

2: front, right, high Cactus

3: back, right, high Cactus

4: front, left, low

Spectroscope, page 35 What colors of light make up visible light? Visible light is made of the colors in the rainbow, or ROYGBIV.

Maze 1 Solve the maze of mirrors! Draw the reflected light wave as it is reflected from mirror to mirror until you reach the last mirror before the light wave leaves the page. This is the final mirror.

HINTS: Every mirror is part of the maze. Focus on the middle of the mirrors.

Does a rainbow have the same colors in the same order as a spectroscope? Students should be able to see that the order is the same in both items.

Reflection, page 36 How is light reflected? Light bounces off of shiny surfaces in a straight line.

How does the angle of the light traveling to the mirror compare to the angle of the reflected light? Students should be able to describe the angles as being similar because of the lines they made with their yarn.

Maze 1 and 2, pages 37-38 Answer keys to the right.

Maze 2

Solar House, page 40 How does the angle of the PV cell to the sun affect the amount of electricity it produces?

Student answers should reflect that different angles make the fan spin faster or slower. The more direct light the cell receives, the faster the fan will turn because it is creating more electricity.

Solve the maze of mirrors! Draw the reflected light wave as it is reflected from mirror to mirror until you reach the last mirror before the light wave travels off the page. This is the final mirror. Every mirror is a part of the maze.

Comparing Light Bulbs, page 41 Which bulb produced more light? More heat? Both bulbs should produce the same amount of light after a short time. However, the incandescent will produce much more heat.

Which bulb do you think is more energy efficient? Explain what you think using your observations above. The CFL is more efficient because it produces the same amount of light but wastes less energy on heat.

Facts of Light, page 43

Cost of bulbs for 25,000 hrs of light

INCANDESCENT BULB $12.50

HALOGEN $12.45

COMPACT FLUORESCENT (CFL) $3.75

LIGHT EMITTING DIODE (LED) $1.33

Total kWh Consumption

1,500 kWh

1,075 kWh

325 kWh

300 kWh

Cost of electricity

$193.35

$138.57

$41.89

$38.67

Life Cycle Cost

$205.85

$151.02

$45.64

$40.00

Light and Lighting Survey, page 45 1. Girl in dark clothing 2. Boy farthest from the sun

© 2019

The NEED Project

3. True 4. True

Light and Lighting www.NEED.org

5. False 6. False

7. True 8. CFL

13

Lab Safety Rules Eye Safety Always wear safety glasses when performing experiments.

Fire Safety Do not heat any substance or piece of equipment unless specifically instructed to do so.

Be careful of loose clothing. Do not reach across or over a flame.

Keep long hair pulled back and secured.

Do not heat any substance in a closed container.

Always use tongs or protective gloves when handling hot objects. Do not touch hot objects with your hands.

Keep all lab equipment, chemicals, papers, and personal items away from the flame.

Extinguish the flame as soon as you are finished with the experiment and move it away from the immediate work area.

Heat Safety Always use tongs or protective gloves when handling hot objects and substances.

Keep hot objects away from the edge of the lab table––in a place where no one will accidentally come into contact with them.

Do not use the steam generator without the assistance of your teacher.

Remember that many objects will remain hot for a long time after the heat source is removed or turned off.

Glass Safety Never use a piece of glass equipment that appears to be cracked or broken.

Handle glass equipment carefully. If a piece of glassware breaks, do not attempt to clean it up yourself. Inform your teacher.

Glass equipment can become very hot. Use tongs or gloves if glass has been heated.

Clean glass equipment carefully before packing it away.

Chemical Safety Do not smell, touch, or taste chemicals unless instructed to do so.

Keep chemical containers closed except when using them.

Do not mix chemicals without specific instructions.

Do not shake or heat chemicals without specific instructions.

Dispose of used chemicals as instructed. Do not pour chemicals back into a container without specific instructions to do so.

If a chemical accidentally touches your skin, immediately wash the area with water and inform your teacher.

14

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Student Informational Text LIGHT IS ENERGY

We use light energy every day. Without light, our lives would be very different. Close your eyes and think about a world without light.

SUNLIGHT

We use light energy for more than seeing. The energy in light helps plants grow. Doctors use special light to help in surgery. We can also use light to make products and electricity.

Light Is Energy In Waves What is light? Light is energy that travels in waves.

All the energy we get from the sun travels in waves.

Some of that energy is in light waves we can see—it is visible light. Some is in waves we can’t see. We can’t see infrared waves, but they can warm us when they touch our skin. We can’t see ultraviolet waves, but they can burn our skin.

Wave Measurements

We measure waves by the distance from the top, or crest, of one wave to the top of the next. This distance is called its wavelength. The shorter the wavelength, the more energy the wave has.

Some waves of energy—like radio waves—are very long. Radio waves can be a mile long. Other waves are very short—like visible light waves and x-rays. There are about 50,000 waves in an inch of visible light.

CREST

LENGTH

HEIGHT

TROUGH

Energy in Waves

Radio waves

© 2019

The NEED Project

Television waves

Light and Lighting

www.NEED.org

Microwaves

Infrared waves

VISIBLE LIGHT

Ultraviolet

Xrays

15

Light Waves Travel In Straight Lines Light waves travel in straight lines. They do not change direction unless they are reflected or refracted.

When light from the sun hits a tree, it cannot pass through it. It cannot go around the tree. Some of the light is absorbed by the tree and the rest is reflected back into the air. An area without light is made—a shadow.

Thousands of years ago, early Egyptians studied shadows. They knew the sun travels the same path in the sky everyday. They knew that shadows change as the sun moves across the sky. They used this knowledge to develop a tool to tell time—a sundial. They placed a stick in the ground. The position and length of the stick’s shadow told the people the time.

An Eclipse Is A Shadow Sometimes the moon moves between the Earth and the sun. The sun’s light cannot pass through the moon to reach the Earth. A large shadow covers the Earth. This is called a solar eclipse.

During an eclipse, some parts of the Earth get no light at all. They become as dark as night. This area is called the umbra. Some parts of the Earth get some light. They are in part shadow, part light. This area is called the penumbra.

Eclipse PENUMBRA UMBRA the sun is the sun is partly hidden totally hidden

Sun Moon

When Light Waves Hit Substances Light waves travel in a straight line. When light waves hit something, three things can happen. The light can travel through a substance and bend—be refracted.

Light passing through transparent substances like water is bent, or refracted.

Light waves can enter a substance and be absorbed.

Plants absorb some light waves and convert them into sugars through photosynthesis. Light waves can also bounce off a substance—be reflected. A mirror reflects light waves. Many substances absorb some light waves and reflect others.

Earth

Photosynthesis In the process of photosynthesis, plants convert radiant energy from the sun into chemical energy in the form of glucose (or sugar).

RADIANT ENERGY

RADIANT ENERGY

CARBON DIOXIDE OXYGEN

OXYGEN

WATER GLUCOSE

16

© 2019

CARBON DIOXIDE WATER

The NEED Project

Light and Lighting

www.NEED.org

Light Has Many Wavelengths Visible light—the wave energy we can see—is made of many colors. Every color has a different wavelength. The longest wavelengths are reds. The medium wavelengths are yellows. The shortest wavelengths are violets. All of the colors mixed together make white light.

A Prism Separates Light Waves A prism is a piece of clear glass or plastic that bends light waves as they pass through it. A prism is often shaped like a triangle.

A prism can separate visible light into its different wavelengths. It can separate all of the colors that make up white light.

A prism bends—or refracts—light waves. The wavelengths of each color bend at a different angle. The light that goes into the prism spreads out as it leaves the prism.

Have you ever seen a rainbow? Rainbows are formed when the sun shines while it is raining. Drops of rain act like tiny prisms to bend the sunlight. The raindrops separate the light waves into colors.

Color Wavelengths RED ORANGE YELLOW GREEN BLUE INDIGO VIOLET

Prism

Water refracts light waves, too. Light can pass through water, but it bends as it goes through. Have you ever noticed that things look different in the bathtub or swimming pool? The water is bending the light. The light waves are refracted as they pass through the water.

We Can Bend Light With a Lens We can use pieces of glass in different shapes—called lenses—to bend light.

ite wh

re oran d yell ge greeow blu n indi e viol go et

ht lig

A convex lens is thicker in the middle than on the ends.

It bends light waves toward a point. A convex lens can make objects look larger.

A concave lens is thinner in the middle than on the ends. It spreads out light waves that pass through it. A concave lens can make objects look smaller.

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Refraction Convex lens

Concave lens

17

We Use Lenses Every Day To Refract Light The human eye has a convex lens. The eye sees light waves bouncing off an object. The lens in the eye refracts the light waves as they pass through it. The light waves hit the retina in the back of the eye. The light waves make an image of the object on the retina. The image on the retina is upside down. When we are babies, our brains quickly learn to turn the images around. Otherwise, everything would look upside down.

If our eyes are not the right shape, we cannot see clearly. The image does not focus on the retina. It is blurry.

We can use lenses in eye glasses to help us see better. The lenses refract the light waves so that they focus the image on the retina. Contact lenses do the same thing.

How Your Eye Works

RETINA LENS

IMAGE OF OBJECT

OBJECT

LIGHT REFLECTED FROM OBJECT

A magnifying glass is a convex lens with a handle.

Telescopes and microscopes have convex lenses, too.

They can make small objects look larger or distant objects appear closer.

The picture on the bottom of the page shows how a convex lens works. Light waves bounce off an object and bend as they pass through the lens. The eye sees the larger image shown by the dotted lines.

A magnifying glass is a convex lens.

Convex Lens

CONVEX LENS

A convex lens refracts light and makes objects appear larger.

LARGER IMAGE

18

HUMAN EYE

ACTUAL OBJECT

Š 2019

The NEED Project

Light and Lighting

www.NEED.org

DISCO BALL

Light Waves Can Be Reflected How do we see things? We see the light waves that bounce off things—the light that is reflected by substances. When you look at an object, you are really seeing reflected light waves. Think about it. When there are no light waves, you can’t see anything.

When you look in the mirror, the image you see is made by light waves. Light from all around you bounces off of you. Some of the light waves travel toward the mirror. The mirror reflects the light waves.

Some of the light waves from the mirror travel toward your eyes. Your eyes see these reflected light waves.

Reflection Of Light Is Predictable Light waves don’t just bounce around. They are reflected at angles we can predict. The reflection of light is a lot like bouncing a round ball on a smooth surface. If you drop the ball straight down, it will bounce straight back up. If you bounce the ball away from you, it will continue to move away from you in a straight line. It won’t bounce to the left or right, or back toward you. It bounces away at the same angle you throw it.

Reflection of Light LIG

HT

WA VE

VE WA T H

Angle A = Angle B

ED ECT

LIG

FL

RE Angle A

Light waves are reflected in the same way. Light waves travel in straight lines. When a light wave hits an object and is reflected, it will be reflected in a straight line. If the light wave hits an object at an angle, it will WHO IS COOLER? be reflected at the same angle.

Angle B MIRROR

Look at the picture to the right. The light wave is traveling toward the mirror at an angle—labeled Angle A. When the light wave hits the mirror, it is reflected at an angle—labeled Angle B. Both angles are the same. Angle A equals Angle B.

Light Waves Can Be Absorbed We know that light waves can pass through a substance and bend—be refracted. Water and prisms refract light waves.

We also know that light waves can hit something and be reflected. We can see objects only because light waves are reflected off the objects and into our eyes.

Light waves can also enter a substance and change into other forms of energy. The light energy can be absorbed by the substance. When we are in the sun, some of the light waves enter our skin and turn into heat. Our bodies absorb some of the light waves.

© 2019

The NEED Project

Light and Lighting

www.NEED.org

19

Black And White Most substances reflect some light waves and absorb others. That’s why we see colors! Visible light is made of every color. Every color has a different wavelength.

Black and White

When a substance absorbs all wavelengths of visible light, the substance looks black. No light waves are reflected to reach our eyes. The light waves—which are waves of energy—enter the substance. The substance changes the light energy to other forms of energy. When a substance reflects all wavelengths of visible light, the substance looks white.

Have you heard that dark colored clothes make you hotter in the sun? That’s because dark colors absorb light waves and light colors reflect them.

Seeing Colors

Colors in a Sunflower

We see many colors because most substances absorb some wavelengths of light and reflect others. We see the colors that are reflected by the substances.

A rose looks red because it is reflecting the red light waves and absorbing the oranges, yellows, blues, greens, and violets.

A blue bird looks blue because it is reflecting blue light waves and absorbing the others. The dirt looks brown because it is reflecting several light waves that together look brown, and absorbing other light waves.

White petals reflect all visible light wavelengths

Yellow centers reflect yellow wavelengths and absorb other wavelengths Green leaves reflect green wavelengths and absorb other wavelengths

Using Light Energy We use light energy every day to see. We use it in many other ways, too. The leaves of plants reflect green light waves and absorb others. The energy they absorb is used by the plants to make sugars through photosynthesis.

These sugars feed the plants and the plants we eat give energy to us. All the energy we get to move and grow comes from plants.

We can use the energy in light to make heat in many ways. We can color things black to absorb the light waves.

We can use mirrors to reflect many light waves onto an object that absorbs them and turns them into heat. We can use this heat to warm houses and water or to cook food.

We can also use light energy to make electricity. Solar cells can absorb light waves and turn the energy into electricity.

20

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Thermometer

Water Boils ºF ºC

Human Body ºF ºC

Water Freezes ºF ºC You see lines across the thermometer to show three temperature readings.

Read both scales of the thermometer and write the temperatures in the blank spaces on the lines.

Now draw lines across the picture to show what you think the temperature is in the classroom, what you think the temperature is outside, and what you think the temperature is of the water in the drinking fountain.

Use a thermometer to measure the actual temperatures of the classroom, outside, and the water in the fountain and draw lines across the picture to show those. © 2019

The NEED Project

Light and Lighting

www.NEED.org

21

Solar Energy to Heat ? Question  What is the relationship between absorbed solar energy and color?

 Hypothesis Before going outdoors, predict which thermometer will be the hottest by numbering the thermometers on the right 1-3, with 1 as the hottest.

Prediction

Result

 Materials 3 Thermometers Black paper White paper

Procedure 1. Put three thermometers in a sunny place.

2. Cover the bulb of one thermometer with black paper. Cover the bulb of one thermometer with white paper. Leave the bulb of the third thermometer uncovered.

F

O 120 110 100 90 80 70 60 50 40 30 20 10 0 -10

C

O

50 40 30

120 110 100 90 80

20

70

10

50

0 -10 -20

F

O

60 40 30 20 10 0 -10

C

O

F

O

50

120

C

O

50

110

40

40

100 90

30

30

80

20

70

10

50

20

60

10

40

0

0

30 20

-10

-10

10 0

-20

-20

-10

3. Record your results by coloring the tubes of the thermometers to the right.

4. Look at the results and re-number the thermometers 1-3 with 1 as the hottest.

 Conclusion 1. Which color absorbed the most energy? What evidence from the activity shows you this?

2. How should this information affect your clothing choices? What color will you wear on a sunny day?

3. Which will be hotter on a sunny day, a car with a dark interior, or a car with a light tan interior? How do you know?

22

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Solar Balloon ? Question  What will happen when the solar balloon is filled with air and taken outside on a sunny day?

 Hypothesis In your science notebook or on a piece of paper, write a prediction to answer the question above. Be sure to support your hypothesis using the concepts you explored in previous activity. Incorporate at least five words from the word bank in your explanation. Circle the words you chose to use!

 Materials Solar balloon Fishing line or lightweight string Sunny day

 Word Bank absorbs air converts gas heat light radiant energy reflection transforms thermal energy

Procedure 1. Take the solar balloon outside. Tie one end of the balloon and fill it with air. When the balloon is full, tie the open end closed. Tie fishing line or lightweight string to the balloon and let it sit in the sunlight. Observe what happens. Record your observations.

 Conclusion 1. Explain what happened to the air inside the balloon and why it rose?

2. Will the balloon fly on a sunny but very cold winter day?

 Extension 1. How might you get the balloon to fly on a cloudy day?

© 2019

The NEED Project

Light and Lighting

www.NEED.org

23

Radiometer ? Question  How does a radiometer turn the sun’s energy into motion?

 Hypothesis Examine the radiometer and predict which way the vanes will spin when it is placed in the sun. Color the PREDICTION ARROW that shows the direction you think the vanes will spin.

Procedure 1. Put the radiometer in bright sunlight and observe the radiometer’s vanes.

2. Record your results. Color the RESULT ARROW that shows the direction the vanes are spinning.

 Conclusion 1. Explain how the radiometer turns the sun’s energy into motion.

 Extension 1. Will the radiometer work in artificial light?

2. Will the vanes of the radiometer spin faster if the light is brighter?

24

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Radiometer Explanation TOP VIEW OF RADIOMETER

Top View of Radiometer Black vanes absorb radiant energy

Air molecules near the black vanes heat up and bump back into black vanes pushing them

White vanes reflect radiant energy

When the radiometer is put in light, the vanes absorb energy. The light energy is changed into heat. The black side of the vane absorbs more of the light energy, and it gets warmer. This causes the air around the vanes to heat up. When the air molecules hit the black side, they bounce back with more energy than when they hit the white side. Since there is more of a push on one side than the other, the vanes begin to turn. The more light energy that reaches the radiometer, the more heat is produced, and the faster the vanes spin. If both sides of the vanes were the same color, the radiometer vanes would never move!

Š 2019

The NEED Project

Light and Lighting

www.NEED.org

25

Glow Sticks & Background Some chemical reactions produce light. Glow sticks have two chemicals inside them. One of the chemicals is in the glass container inside the glow stick. If you bend the glow stick and break the glass container, the chemicals react and form a new chemical. The chemical reaction also produces light.

?

Question

How does heat affect the light produced by a glow stick?

 Hypothesis Read the procedure and make a prediction to answer the question.

 Materials 2 Glow sticks Cup of ice water Cup of warm water

Procedure 1. Bend the glow sticks until the glass containers inside break, then shake to mix the chemicals. Observe the amount of light the glow sticks produce.

2. Place one glow stick in ice water and one in warm water. Observe any changes to the glow sticks.

 Conclusion 1. Explain how heat affects the chemical reaction in a glow stick.

How a Glow Stick Works Plastic Casing

1

Glass Container Hydrogen Peroxide Solution

Ester and Dye

2

3 1. The glow stick is filled with a chemical compound called an ester and dye. Inside, a small glass container is filled with hydrogen peroxide.

2. When the glow stick is bent and the container is broken, the chemicals from the ampule and the glow stick mix, causing a chemical reaction.

3. During the chemical reaction, energy is released as light.

26

© 2019

The NEED Project

Light and Lighting

www.NEED.org

NaturePrint® Paper ? Question  How does sunlight affect the chemicals in different kinds of paper?

 Hypothesis Predict how sunlight will affect NaturePrint® Paper.

 Materials 1 Cut-out of the sun Sheet of NaturePrint® Paper Objects found outside or brought from home

Procedure 1. Cut out the sun picture on page 28.

2. Place the sun picture and/or your objects on the NaturePrint® Paper.

3. Place the piece of paper in direct sunlight.

4. After two minutes, pick up the NaturePrint® Paper and carefully carry it to the shade.

5. Remove the objects and sun picture and place the NaturePrint® Paper in water for one minute.

6. Allow the NaturePrint® Paper to dry.

7. Record what you see when looking at your dried NaturePrint® Paper on your observation chart.

© 2019

The NEED Project

Light and Lighting

www.NEED.org

27

28

© 2019

The NEED Project

Light and Lighting

www.NEED.org

 Observations Make a diagram of your piece of dried NaturePrint® Paper below.

Side with Sun Cutout

Side with Objects You Chose

 Conclusion 1. Describe how your NaturePrint® Paper changed over time. Explain why you think this occurred.

 Extension 1. Will a similar reaction occur with colored construction paper if left in the sun?

2. Will a similar reaction occur with colored cloth?

© 2019

The NEED Project

Light and Lighting

www.NEED.org

29

UV Beads & Background UV stands for Ultra Violet light, a type of radiation or energy that travels in a wave-like pattern. UV light is found within sunlight but is invisible. You are probably aware of the effects of UV radiation because you wear sunscreen and sunglasses to protect you from it. UV light produces chemical reactions that can cause a substance to glow or fluoresce, or your skin to burn or tan. It also causes the formation of Vitamin D, an essential vitamin for humans and other organisms. A good amount of harmful UV radiation gets blocked by the ozone layer, but the little amounts that get through will lead to these chemical changes. UV beads contain special color-changing pigments that are sensitive to UV light from the sun and other sources. ? Question  What will happen to the beads in the sun?

 Hypothesis Predict how sunlight will affect the UV beads.

 Materials 5 UV beads 1 Pipe cleaner

Procedure 1. String the UV beads on the pipe cleaner. Twist the pipe cleaner into a loosely-fitting bracelet and wear on your wrist.

2. Take your bracelet outside. Observe what happens to your beads.

3. Compare your bracelet to the teacher’s bag of beads with sunscreen.

 Conclusion 1. What happened to your beads outside in the sun?

2. How does sunscreen affect the UV beads?

 Extension 1. Will the beads do the same thing inside as they do in the sunlight? Why or why not?

30

© 2019

The NEED Project

Light and Lighting

www.NEED.org

How Light Travels ?

Question

Does light travel in a predictable way?

 Hypothesis Read the procedure and make a prediction to answer the question.

 Materials 1 Flashlight 2 Pieces of cardboard Sharp pencil Clay

Procedure 1. With a pencil, make a hole in the same place in each piece of cardboard.

2. Use the clay to hold the pieces of cardboard upright. Use the diagram below to set up the pieces of cardboard.

3. Shine the light from the flashlight through the holes in the cardboard. You might have to move one of the pieces of cardboard until you can shine the light through both holes and onto the wall.

4. Observe the path that the light travels from the flashlight to the wall.

 Conclusion 1. How does light travel?

 Extension 1. Look at the light bulb in the flashlight. Why do you think there is shiny metal behind the bulb?

2. Is it better to read with an overhead light or a desk light? Why?

© 2019

The NEED Project

Light and Lighting

www.NEED.org

31

Making Shadows & Background Shadows are areas where light doesn’t reach. Explore the different shadows that a crayon makes when you move the light source.

?

Question

What causes a change in the shape or size of a shadow?

 Hypothesis Predict how you can change a shadow.

 Materials Crayon Piece of clay

Ruler Flashlight

Procedure 1. Place a crayon in a piece of clay so that it is standing straight up.

2. Move the flashlight at different distances from and angles to the crayon and observe the shadows, like in the pictures below.

 Conclusion 1. What variables affect the size and shape of an object’s shadow?

32

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Where is the Sun? Circle the location of the sun in each picture. You can circle more than one location.

1.

2.

Front Back

Front Back

Left Right

Left Right

High Low Overhead

High Low Overhead

3.

4.

Front Back

Front Back

Left Right

Left Right

High Low Overhead

High Low Overhead

© 2019

The NEED Project

Light and Lighting

www.NEED.org

33

Hand Shadows

34

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Spectroscope & Background A spectroscope separates visible light into individual colors of light, a lot like a prism. Drops of water can also act like a prism and separate light into the colors of a rainbow.

?

Question

What colors of light make up visible light?

 Hypothesis Read the procedure and write a hypothesis to answer the question.

 Materials 1 Spectroscope Flashlight Colored pencils or crayons Spray bottle filled with water

Procedure 1. Look into the round circle end of the spectroscope, aiming it toward the flashlight or another bright light.

Turn the spectroscope until you see a band of colors off to the side.

2. In the box below, draw the colors in the order you see them.

3. Go outside on a sunny day with the spray bottle filled with water. Spray the water into the air. Have the other students walk around until they see a rainbow in the spray of water.

 Conclusion 1. What colors of light make up visible light?

2. Does a rainbow have the same colors in the same order as a spectroscope?

 Extension 1. How would colored glasses change the colors you would see in the spectroscope?

© 2019

The NEED Project

Light and Lighting

www.NEED.org

35

Reflection & Background When light hits a flat, shiny object like a mirror, it is reflected. It bounces off the object.

?

Question

How does light behave when it is reflected from an object?

 Hypothesis Read and predict how you think mirrors affect light.

 Materials Mirror Flashlight Piece of yarn 2 Partners

Procedure 1. Place the mirror face up on the floor. Stand three feet from the mirror and shine the flashlight beam onto the mirror. Hold the flashlight at the eye level of your partner.

2. Have your partner stand on the other side of the mirror and move around until he/she finds the beam of reflected light. Observe the distance of your partner from the mirror.

3. Hold the flashlight at waist level. Have the partner move until he/she finds the beam. Observe the distance of your partner from the mirror.

4. Move back several feet and see if you and your partner can figure out where he/she should stand to see the beam of light.

5. Use a long piece of yarn to show the path of the light. Hold one end of the yarn to the end of the flashlight.

Have someone stretch out the yarn straight to the mirror, then to your partner at eye level.

6. Observe the angles that the yarn makes from the ground.

 Conclusion 1. How is light reflected?

2. How does the angle of the light traveling to the mirror compare to the angle of the reflected light?

36

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Maze 1 Solve the maze of mirrors! Draw the reflected light wave as it is reflected from mirror to mirror until you reach the last mirror before the light wave leaves the page. This is the final mirror.

HINTS: Every mirror is part of the maze. Focus on the middle of the mirrors.

Š 2019

The NEED Project

Light and Lighting

www.NEED.org

37

Maze 2 Solve the maze of mirrors! Draw the reflected light wave as it is reflected from mirror to mirror until you reach the last mirror before the light wave travels off the page. This is the final mirror. Every mirror is a part of the maze.

38

Š 2019

The NEED Project

Light and Lighting

www.NEED.org

Photovoltaic Cells Explanation Step 1

When the two wafers are placed together, the free electrons from the n-layer are attracted to the p-layer.

An interesting thing happens at the moment of contact between the two wafers--free electrons from the n-layer flow into the p-layer for a split second, then form a barrier to prevent more electrons from moving from one layer to the other. This contact point and barrier is called the p-n junction. Once the layers have been joined, there is a negative charge in the p-layer section of the junction and a positive charge in the n-layer section of the junction. This imbalance in the charge of the two layers at the p-n junction produces an electric field between the p-layer and the n-layer.

A location that can accept an electron Free electron Proton Tightly-held electron

STEP 1 NEGATIVE CHARACTER

n-type silicon p-type silicon

POSITIVE CHARACTER

electric field

STEP 2 POSITIVE CHARGE

STEP 4

n-type p-n junction p-type

NEGATIVE CHARGE

PHOTONS

STEP 3 electric field

Step 2

From Silicon to Electricity

electric field

Pure silicon is used to form very thin wafers. In some of these wafers, a small amount of the element phosphorous is added. In the other wafers, a small amount of the element boron is added. The phosphorous gives its wafer an excess of free electrons; therefore, this wafer will have a negative character.

This wafer is called the n-layer. The n-layer is not a charged wafer--it has an equal number of protons and electrons--but some of the electrons are not held tightly to the atoms. They are free to move about. The boron gives its wafer a positive character, because it has a tendency to attract electrons. This layer also has an equal number of protons and electrons--it has a positive character but not a positive charge. This wafer is called the p-layer.

POSITIVE CHARGE

SUN n-type p-n junction p-type

NEGATIVE CHARGE

SUN sun

FREE ELECTRON

load

Step 3 If the PV cell is placed in the sun, photons of light energy strike the electrons in the p-n junction and energize them, knocking them free of their atoms. These electrons are attracted to the positive charge in the n-layer and are repelled by the negative charge in the p-layer.

Step 4 A wire can be attached from the p-layer to the n-layer. As the free electrons are pushed into the n-layer, they repel each other. The wire provides a path for the electrons to flow away from each other. This flow of electrons is an electric current.

Š 2019

The NEED Project

Light and Lighting

www.NEED.org

39

Solar House & Background A photovoltaic (PV) cell changes radiant energy into electricity. Electricity can run a motor to make a fan move.

?

Question

How can we use the sun’s energy to make electricity?

 Hypothesis Predict how you think the solar panel will work in the sun.

 Materials PV cell kit Shoe box Scissors Sharp pencil

Procedure 1. Make a shoe box into a house with big windows and a door in the front.

2. Make a hole in the top of the box with the pencil. Place the PV cell on top of the house.

3. Put the stem of the motor through the hole. Push the hole in the fan onto the stem of the motor that is sticking through the ceiling.

4. On a sunny day, place the house in the sun. Observe the fan turn as the PV cell turns radiant energy from the sun into electricity and then into motion.

5. Tilt the PV cell at different angles to the sun and observe the speed of the turning fan.

 Conclusion 1. How does the angle of the PV cell to the sun affect the amount of electricity it produces?

 Extension 1. Make a list of ten ways you could use a PV cell at home.

40

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Comparing Light Bulbs ?

Question

Which bulb produces more heat?

 Hypothesis Read the procedure and make a prediction to answer the question.

 Materials Lamp Incandescent bulb LED bulb CFL bulb Thermometers

Procedure 1. Put the incandescent bulb into the lamp and turn it on. Observe the amount of light and heat that the bulb produces. Be very careful not to touch the bulb; it can get very hot.

2. Turn off the lamp and let the bulb cool.

3. Take the incandescent bulb out of the lamp and put in the compact fluorescent bulb. Turn on the lamp.

Observe the amount of light and heat the bulb produces.

4. Repeat for LED bulb. *If you have three lamps, you can compare the bulbs at the same time.

 Conclusion 1. Which bulb produced the most light? More heat?

2. Which bulb do you think is most energy efficient? Explain why you think this, using your observations above.

 Extension 1. Examine the packaging of different types of light bulbs with similar lumen output.

2. Considering the cost of the bulb, the amount of energy it uses, and the number of hours it will last, calculate which bulb is the best buy.

© 2019

The NEED Project

Light and Lighting

www.NEED.org

41

Facts of Light Years ago, we used a lot of energy in the form of electricity to make light to be able to see. Thirty percent of the electricity schools used was for lighting, and homes used about 14 percent of their electricity consumption for lighting. That’s because homes, schools, and other commercial buildings used a lot of incandescent lighting. These inefficient bulbs were perfected by Thomas Edison in 1879 and didn’t change much for the next 125 or more years! These bulbs were surprisingly inefficient, converting up to 90 percent of the electricity they consumed into heat.

The Energy Independence and Security Act of 2007 changed the standards for the efficiency of light bulbs used most often. As of 2014, most general use bulbs must be 30 percent more efficient than traditional, inefficient incandescent bulbs. What do the new standards mean for consumers? The purpose of the new efficiency standards is to give people the same amount of light using less energy. Most incandescent light bulbs have since been phased out and are no longer available for sale. This has resulted in significant energy savings for homes and schools. Newer, efficient lighting now accounts for only 17 percent of the electricity used in schools, and under 20 percent used in homes.

There are several lighting choices on the market that meet the new efficiency standards. Energy-saving incandescent, or halogen, bulbs are different than traditional, inefficient incandescent bulbs because they have a capsule around the filament (the wire inside the bulb) filled with halogen gas. This allows the bulbs to last three times longer and use 25 percent less energy.

Compact fluorescent light bulbs (CFLs) provide the same amount of light as incandescent bulbs, but use up to 75 percent less energy and last ten times longer. CFLs produce very little heat. Using CFLs can help cut lighting costs and reduce environmental impacts. Today’s CFL bulbs fit almost any socket, produce a warm glow and, unlike earlier models, no longer flicker and dim. CFLs have a small amount of mercury inside and should always be recycled rather than thrown away. Many retailers recycle CFLs for free.

Light emitting diodes, better known as LEDs, are gaining in popularity. Once used mainly for exit signs and power on/off indicators, improved technology and lower prices are enabling LEDs to be used in place of incandescents and CFLs. LEDs are one of the most energy-efficient lighting choices available today. LEDs use 75 percent less energy than traditional incandescents, and have an average lifespan of at least 25,000 hours. The cost of LEDs has dropped in the last five years and may continue to drop. They use even less energy than CFLs, save more electricity, and produce fewer carbon dioxide emissions. The U.S. Department of Energy estimates that widespread adoption of LED lighting by 2027 would reduce lighting electricity demand by 33 percent. This would avoid construction of 40 new power plants.

42

INCANDESCENT BULB

HALOGEN

COMPACT FLUORESCENT (CFL)

LIGHT EMITTING DIODE (LED)

Brightness

850 lumens

850 lumens

850 lumens

850 lumens

Life of Bulb

1,000 hours

3,000 hours

10,000 hours

25,000 hours

Energy Used

60 watts = 0.06 kW

43 watts = 0.043 kW

13 watts = 0.013 kW

12 watts = 0.012 kW

Price per Bulb

$0.50

$1.50

$1.50

$1.33

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Facts of Light The graphic on the previous page shows four light bulbs that produce the same amount of light. You might use bulbs like these as a bright overhead light. One bulb is an incandescent light bulb (IL), one is a halogen, one is a compact fluorescent light (CFL), and another is a light emitting diode (LED). Which one is the better bargain? Let’s do the math and compare the four light bulbs using the residential cost of electricity at $0.13/kWh. 1. Determine how many bulbs you will need to produce 25,000 hours of light by dividing 25,000 by the number of hours each bulb produces light.

2. Multiply the number of bulbs you will need to produce 25,000 hours of light by the price of each bulb. The cost of each bulb has been given to you.

3. Multiply the wattage of the bulbs (using the kW number given) by 25,000 hours to determine kilowatt-hours (kWh) consumed.

4. Multiply the number of kilowatt-hours by the cost per kilowatt-hour to determine the cost of electricity to produce 25,000 hours of light.

5. Add the cost of the bulbs plus the cost of electricity to determine the life cycle cost for each bulb. Which one is the better bargain?

All bulbs provide about 850 lumens of light.

COST OF BULB

INCANDESCENT BULB

HALOGEN 3,000 hours

COMPACT FLUORESCENT (CFL)

LIGHT EMITTING DIODE (LED)

1,000 hours

10,000 hours

25,000 hours

$0.50

$1.50

$1.50

$1.33

COST OF ELECTRICITY

INCANDESCENT BULB

HALOGEN

COMPACT FLUORESCENT (CFL)

LIGHT EMITTING DIODE (LED)

Total Hours Wattage

25,000 hours 60 watts = 0.060 kW

25,000 hours 43 watts = 0.043 kW

25,000 hours 13 watts = 0.013 kW

25,000 hours 12 watts = 0.012 kW

$0.13

$0.13

$0.13

$0.13

INCANDESCENT BULB

HALOGEN

COMPACT FLUORESCENT (CFL)

LIGHT EMITTING DIODE (LED)

Life of bulb (how long it will light)

Number of bulbs to get 25,000 hours

x Price per bulb = Cost of bulbs for 25,000 hours of light

x = Total kWh consumption x Price of electricity per kWh = Cost of Electricity LIFE CYCLE COST

Cost of bulbs

+ Cost of electricity = Life cycle cost

© 2019

The NEED Project

Light and Lighting

www.NEED.org

43

OFF

Home Energy Use Survey

Be an Energy Detective Complete this survey to begin to understand how much energy is used in your home. If you are not sure about a question, ask an adult for help.

1. Number of incandescent light bulbs in your home. _________________ 2. Number of CFL or LED light bulbs in your home. _________________ 3. Number of times your dishwasher is run per week. _________________ 4. How often the Energy Saver feature on the dishwasher is used.

0% 25%

50%

75%

100%

5. Number of loads of laundry washed per week. ______________________ 6. Percentage of the laundry loads washed and rinsed in cold water.

0% 25%

50%

75%

7. Total number of baths taken by all family members each week.

100%

____________

8. Total number of showers taken by all family members each week.

_____________

9. Average length of each shower. _______ minutes 10. Water heater temperature is set at 120°F or lower.

11. Water heater is wrapped in an insulated blanket.

yes______ no_______ yes______ no_______

12. Thermostat settings: Cooling Season: Day ________°F

Night ________°F

Heating Season: Day ________°F

Night ________°F

13. Fans are used instead of air conditioning in warm weather.

yes______ no_______

14. Window blinds are closed on hot, sunny days and open on cold, sunny days.

yes______ no_______

15. How many times a day: is a light left on in an unoccupied room? ____________________ is a TV, radio, computer, or video game left on with no one using it? ____________________ is the water allowed to run needlessly when brushing teeth or washing dishes? ____________________ is the stove or oven used to cook instead of the microwave or toaster oven? ____________________ is a door or window open when the heat or air conditioning is on? ____________________

44

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Light and Lighting Survey 1. Circle the girl who would feel hotter.

2. Circle the boy who would have the longest shadow.

3. Light can be reflected or absorbed.

True

False

4. Some substances can store light.

True

False

5. A mirror absorbs light. True False 6. A PV cell turns light energy into heat.

True

False

7. Chemical reactions can produce light.

True

False

8. Circle the light bulb that is most energy efficient.

Š 2019

The NEED Project

Light and Lighting

www.NEED.org

45

Youth Energy Conference and Awards

Youth Awards Program for Energy Achievement

The NEED Youth Energy Conference and Awards gives students more opportunities to learn about energy and to explore

All NEED schools have outstanding classroom-based programs in which students learn about energy.

Does your school have student leaders who extend these activities into their communities? To recognize outstanding achievement and reward student leadership, The NEED Project conducts the National Youth Awards Program for Energy Achievement.

energy in STEM (science, technology, engineering, and math).

The annual June conference has students from across the country working in groups on an Energy Challenge designed to stretch their minds and energy knowledge. The conference culminates with the Youth Awards Ceremony recognizing student work throughout the year and during the conference.

For More Info: www.youthenergyconference.org

Share Your Energy Outreach with The NEED Network!

This program combines academic competition with recognition to acknowledge everyone involved in NEED during the year—and to recognize those who achieve excellence in energy education in their schools and communities.

What’s involved?

Students and teachers set goals and objectives and keep a record of their activities. Students create a digital project to submit for judging. In April, digital projects are uploaded to the online submission site.

Want more info? Check out www.NEED.org/Youth-Awards for more application and program information, previous winners, and photos of past events.

46

© 2019

The NEED Project

Light and Lighting

www.NEED.org

Light and Lighting Evaluation Form State: ___________ Grade Level: ___________ Number of Students: __________ 1. Did you conduct the entire unit?



Yes



No

2. Were the instructions clear and easy to follow?



Yes



No

3. Did the activities meet your academic objectives?



Yes



No

4. Were the activities age appropriate?



Yes



No

5. Were the allotted times sufficient to conduct the activities?



Yes



No

6. Were the activities easy to use?



Yes



No

7. Was the preparation required acceptable for the activities?



Yes



No

8. Were the students interested and motivated?



Yes



No

9. Was the energy knowledge content age appropriate?



Yes



No

10. Would you teach this unit again?

Please explain any ‘no’ statement below.



Yes



No

How would you rate the unit overall?



excellent 

good



fair



poor

How would your students rate the unit overall?



excellent 

good



fair



poor

What would make the unit more useful to you?

Other Comments:

Please fax or mail to: The NEED Project

© 2019

8408 Kao Circle Manassas, VA 20110 FAX: 1-800-847-1820

The NEED Project

Light and Lighting

www.NEED.org

47

National Sponsors and Partners Association of Desk and Derrick Clubs Foundation Alaska Electric Light & Power Company American Electric Power Foundation American Fuel & Petrochemical Manufacturers Armstrong Energy Corporation Association for Learning Environments Robert L. Bayless, Producer, LLC Baltimore Gas & Electric BG Group/Shell BP America Inc. Blue Grass Energy Bob Moran Charitable Giving Fund Boys and Girls Club of Carson (CA) Buckeye Supplies Cape Light Compact–Massachusetts Central Alabama Electric Cooperative Citgo CLEAResult Clover Park School District Clovis Unified School District Colonial Pipeline Columbia Gas of Massachusetts ComEd ConocoPhillips Constellation Cuesta College Cumberland Valley Electric David Petroleum Corporation David Sorenson Desk and Derrick of Roswell, NM Desert Research Institute Direct Energy Dominion Energy, Inc. Dominion Energy Foundation DonorsChoose Duke Energy Duke Energy Foundation East Kentucky Power EduCon Educational Consulting Edward David E.M.G. Oil Properties Energy Trust of Oregon Ergodic Resources, LLC Escambia County Public School Foundation Eversource Exelon Exelon Foundation Exelon Generation First Roswell Company Foundation for Environmental Education FPL The Franklin Institute George Mason University – Environmental Science and Policy Gerald Harrington, Geologist Government of Thailand–Energy Ministry Grayson RECC Green Power EMC Greenwired, Inc. ©2019 The NEED Project

Guilford County Schools–North Carolina Gulf Power Harvard Petroleum Hawaii Energy Houston LULAC National Education Service Centers Illinois Clean Energy Community Foundation Illinois International Brotherhood of Electrical Workers Renewable Energy Fund Illinois Institute of Technology Independent Petroleum Association of New Mexico Jackson Energy James Madison University Kansas Corporation Commission Kentucky Office of Energy Policy Kentucky Environmental Education Council Kentucky Power–An AEP Company Kentucky Utilities Company League of United Latin American Citizens – National Educational Service Centers Leidos Linn County Rural Electric Cooperative Llano Land and Exploration Louisiana State University – Agricultural Center Louisville Gas and Electric Company Midwest Wind and Solar Minneapolis Public Schools Mississippi Development Authority–Energy Division Mississippi Gulf Coast Community Foundation National Fuel National Grid National Hydropower Association National Ocean Industries Association National Renewable Energy Laboratory NC Green Power Nebraskans for Solar New Mexico Oil Corporation New Mexico Landman’s Association NextEra Energy Resources NEXTracker Nicor Gas Nisource Charitable Foundation Noble Energy North Carolina Department of Environmental Quality North Shore Gas Offshore Technology Conference Ohio Energy Project Oklahoma Gas and Electric Energy Corporation Opterra Energy Oxnard Union High School District Pacific Gas and Electric Company PECO Pecos Valley Energy Committee People’s Electric Cooperative Peoples Gas Pepco Performance Services, Inc. Petroleum Equipment and Services Association Permian Basin Petroleum Museum

8408 Kao Circle, Manassas, VA 20110

1.800.875.5029

www.NEED.org

Phillips 66 Pioneer Electric Cooperative PNM PowerSouth Energy Cooperative Providence Public Schools Quarto Publishing Group Prince George’s County (MD) R.R. Hinkle Co Read & Stevens, Inc. Renewable Energy Alaska Project Resource Central Rhoades Energy Rhode Island Office of Energy Resources Rhode Island Energy Efficiency and Resource Management Council Robert Armstrong Roswell Geological Society Salal Foundation/Salal Credit Union Salt River Project Salt River Rural Electric Cooperative Sam Houston State University Schlumberger C.T. Seaver Trust Secure Futures, LLC Shell Shell Carson Shell Chemical Shell Deer Park Shell Eco-Marathon Sigora Solar Singapore Ministry of Education Society of Petroleum Engineers Sports Dimensions South Kentucky RECC South Orange County Community College District SunTribe Solar Sustainable Business Ventures Corp Tesla Tri-State Generation and Transmission TXU Energy United Way of Greater Philadelphia and Southern New Jersey University of Kentucky University of Maine University of North Carolina University of Rhode Island University of Tennessee University of Texas Permian Basin University of Wisconsin – Platteville U.S. Department of Energy U.S. Department of Energy–Office of Energy Efficiency and Renewable Energy U.S. Department of Energy–Wind for Schools U.S. Energy Information Administration United States Virgin Islands Energy Office Volusia County Schools Western Massachusetts Electric Company Eversource