Unit 11 – Sound and Light

11 Sound and Light

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In this chapter you will ... • describe how sound is made. • describe how sounds can be different. • list sources of light we use during the day and at night. • list some ways we use sound and light. How do people use light? Where does the light come from? egal Regal l ha soun how soun ources of st some ways e r you du the 132

What things around us make sound? Go Online! Access interactive content relating to this topic on the NGScience website. ngscience.com uca What thi us ma tion n e! interactiv ent relatin this topic on NGScience ngscienc How do people use sound?

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Go Online!

What Is Sound? Close your eyes and listen to the on What Is S Close your ose yourducation Try and guess the things around you. What can hings arongs ar you hear? The things you can hear are sounds. Sound is a form of energy. secret sounds on the NGScience website. QuickCode: G4S2 yo The thTh souna hea What sounds can you hear around you? What is making the sounds?

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What Makes Sounds?

Stretch an elastic band over a cup. Pluck the elastic band. What do you see? What do you hear? When you pluck the elastic band, it moves back and forth very quickly – it vibrates. When something vibrates, it makes sound.

How does a guitar make sound?

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Activities 11.1 – 11.3ed d

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Describing Sounds Sounds can be loud or soft. A jackhammer makes a loud sound. When you whisper, you make a soft or quiet sound. List some sounds you hear from day to day. Group them as loud or soft sounds. Engineer It! Use materials to design a device that makes different sounds. Regal al l aleducat g Sounds ounds n be be loud o o hammer m mmer m sound. ound. When you w en you w soft or quie ft or qu e

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Sounds can be high or low. The chirp of a baby chick is a high sound. A moo of a cow is a low sound. ca Try This! With your friends, talk about the different sounds animals make. Which animals make high sounds? Which animals make low sounds? Activity 11.4AB al 11.4 education w. hick is a k is a low sou ow sou

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Using Sound We use sound in many different ways. We make and use sound when we talk, laugh, cry and sing. ducat und ound in man d in ma We make an make an we talk, lau

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Things we use, like televisions, radios and computers, make sounds. Sounds made by alarms and sirens are used to alert people.ducat s and and rt people. eople. What are some other ways we use sound?

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What Is Light?

Look out of a window during w during uring the day. What do you see? ou see? see? You can see the things outside hings outsid ngs outsi because of light. . Light is a form Light is a f of energy that helps us to see. t helps us tolps us to During the day, the light from the Sun helps us to see. What are some things that help you to see at night?du day, the ligay, the lig helps us to sps us to sucWhat are s help you

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At night there is no Sun to light up the things around us. People use light bulbs, flashlights and candles to help see at night.

Amazing Fact!

Sometimes the moon lights up the sky at night. The light from the moon comes from the Sun!

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Go Online!

Watch a video about sources of light on the NGScience website. QuickCode: S7Z9

Sources of Light f Light ght

Something that gives out light of at gives o its own is called a source of lighted so . Some sources of light are found sources of in nature. The Sun is a source of re. The S light. Fire and lightning are sources ire nd of light too. ight too.

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Flashlights, light bulbs and televisions are sources of light made by people.

AB Activities 11.5 – 11.7

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Try This!

Use a flashlight and your hand to make shadows of different shapes. See if your friends can make the same shaped shadows.

Light and Shadows

Sometimes an object can block block light and make a shadow. A shadow is a dark area. a.

Look at the shape of the hand and the shape of the shadow. What do you notice? Activity 11.8AB caat e shape o d the sha w. What duc Activity 11.d

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The shape of a shadow is similar to the shape of the object making the shadow. What things are causing the shadows in the photographs?ation at led e

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Using Light

During the day, we use the light from e light fro ucation the Sun to help us see the things e things around us. At night, we use lights to light up our cities, streets and homes.

Go Online! Watch a video on the ways we use light on the NGScience website. QuickCode: M2U9 ligh d home Rega ga ne! s we n the ience website ckCode 2U li 146

Cars have headlights that help drivers s that he see at night. Lights also help us to see underwater p us to se and underground. round. You use light when you watch television, play video games, use a computer or use a mobile phone. What are some other ways we use light?gal al W w ght whe on, play v uter or e

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A Closer Look Fireflies

Some animals can make light of their own.

Fireflies are beetles that produce light in their abdomens. They use light to signal other fireflies. Their light also tells other animals ‘Don’t eat me. I taste bad!’.

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Because fireflies produce light of their own – they are a source of light.

See if you can find other animals that produce light of their own.

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Science Words

sound vibrate loud soft high low light source of light shadow

Review

1. True or false. (a) We can hear sounds. (b) Sound is made when something vibrates. 2. Write ‘loud’ or ‘soft’ to describe the sounds. (a) (b) education ca hen somet to descr (c) (d)

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(a) (b) 3. Write ‘high’ or ‘low’ to describe the sounds. n 4. True or false. (a) Light is not a form of energy. (b) Light helps us to see the things around us. 5. List two sources of light. 6. What forms when light is blocked by an object? 7. What is causing the shadows? (a) (b) 8. List three ways you use light. Regal sing List three educat gy e things a ht. light is blo esha

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In the Field

An orchestra is a group of group ofo people that play pe musical instruments together to make music. s togethe It is important that they play at the right time that tat pl and they don’t play too loud or too soft. n’t play toolay A conductor is a person who stands at the ctor is a persois a front of an orchestra and lets the musicians f an orchestrahes know when to play their instrument. They w when to playhe wave their hands to tell the musicians how ve their handsei fast, loud and soft they should play. ast, loud and sud n

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