What is light like

absorb color eye light mirror opaque refl ect shadow Picture Credits Illustration 6 Robert Bob Kayganich.. When light from an object refl ects from a mirror, the light travels together i

Genre Comprehension Skill Text Features Science Content

Nonfi ction Predict • Captions

• Diagrams

• Glossary

Light

Scott Foresman Science 3.2

Standards Preview

Standard Set 2 Physical Sciences

2 Light has a source and travels in a

direction As a basis for understanding

this concept:

2.a Students know sunlight can be

blocked to create shadows.

2.b Students know light is reflected

from mirrors and other surfaces.

2.c Students know the color of light

striking an object affects the way the object is seen.

2.d Students know an object is seen

when light traveling from the object enters the eye.

ISBN 0-328-23521-0 ì<(sk$m)=cdfcbg< +^-Ä-U-Ä-U

What Is Light

Like?

by Kristin Cashore

Physical Sciences

absorb

color

eye

light

mirror

opaque

refl ect

shadow

Picture Credits

Illustration

6 Robert (Bob) Kayganich.

Photographs

Every effort has been made to secure permission and provide appropriate credit for photographic material The

publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions.

Unless otherwise acknowledged, all photographs are the copyright of Dorling Kindersley, a division of Pearson.

Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).

Opener: ©Paul A Souders/Corbis; 1 ©Steve Gorton/DK Images.

ISBN: 0-328-23521-0

Copyright © Pearson Education, Inc All Rights Reserved Printed in the United States of America

This publication is protected by Copyright, and permission should be obtained from the publisher prior to any

prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic,

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Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.

1 2 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06

by Kristin Cashore

What Is Light

Like?

What is light,

anyway?

Light is a form of energy Light travels in straight

lines away from its source On Earth, we get light from

things such as lightbulbs, lanterns, and candles But what

is our biggest source of light? The Sun! Light moves

outward from the Sun in all directions Some of this light

hits Earth

Light from a candle or a ceiling lamp also moves

outward in all directions The light from a car headlight,

though, shines in only one direction The light is blocked

from shining in other directions

The Sun is our biggest

source of light.

Light travels out from a candle fl ame

in every direction.

Opaque Objects

You know that light moves in a straight line What does this mean? Light does not bend or turn corners to

get around opaque objects Opaque objects are objects

that block light

Light hits objects that are in its way Some objects stop light from continuing to move in the same direction

A car or an airplane is opaque It blocks light from traveling in the same direction

An airplane is an opaque object.

Shadows

Sometimes when an object blocks light, it creates

a shadow A shadow is an area that does not receive

light directly Think of a tall building on a sunny day

The building blocks the sunlight Behind the building, a

shadow forms Shadows always form behind objects, on

the opposite side from the light source

Light can make different kinds of shadows Light

shining above an object makes a shadow that is about the

same size as the object Light hitting the side of an object

makes a shadow of a different shape and size

A shadow is formed

when a cup full of

pencils blocks light.

5

Shadows have different kinds of edges If an object is close to the surface where its shadow forms, the shadow will have sharp edges The shadow of a person standing

on the sidewalk will have sharp edges

If an object is far away from the surface where the shadow forms, the shadow will have fuzzy edges A bird

fl ying in the sky will have a shadow with fuzzy edges

The size and shape of a shadow depends on where the light is coming from

Seeing with Light

How does your eye see? Your eye is the part of your

body that is sensitive to light energy Look at the picture

below First, light enters your eye It passes through your

eye’s clear covering It hits the back of your eye, and

forms an upside-down image there

Next, your eyes sends a signal to your brain Your

brain fl ips the image so that it is right-side-up Your brain

helps you understand what you are seeing

The parts of the eye work together to send an image

to the brain.

7

What happens if an opaque object comes between the eye and the original object? Put a car in front of a dog

The car blocks the light coming from the dog The eye can no longer see the dog Can you think of the reason why? It’s because light travels in a straight line!

The car is an opaque object.

It blocks the light from the original object from reaching your eye.

Refl ection

You know that light travels in a straight line What

happens to a line of light when it hits an object? Will it

disappear? No! When light hits an object, some of it will

refl ect, or bounce off, the object The light that refl ects

will keep moving in a straight line But now it will be

moving in a different direction

A mirror refl ects the light from the

girl’s fl ashlight back onto her shirt

9

Most objects that you see do not make their own light Instead, they refl ect light Refl ected light allows you

to see How can you see the cup you are drinking from?

Light from the Sun or another source hits the cup The light refl ects off the cup When the refl ected light reaches your eyes, you see the cup

Why can’t you see anything in a dark room? Because there is no light refl ecting off of the objects in the room!

10

Mirrors

A mirror is a surface made of shiny material A

mirror refl ects light in a very organized way When light

from an object refl ects from a mirror, the light travels

together in a different direction toward your eye A

clear image of the object is refl ected in the surface of the

mirror

This fl at mirror keeps light from

this person’s face from scattering in

many directions.

11

Other Objects

Most objects do not have shiny surfaces Look around your classroom Desks, chairs, and even people have uneven surfaces Light coming from an object that refl ects off an object with rough surfaces is scattered in many different directions You cannot see other objects refl ected

in an object that has an uneven surface When you look

at such an object, all you can see is the object

The table has a rough surface You cannot see anything refl ected in its surface.

How does color

happen?

Objects in Sunlight

Sunlight is made of many different colors of light

They combine to form white light When sunlight hits

most objects, the objects absorb, or take in, some of this

light The objects refl ect the rest of this light The light

that refl ects from an object makes the color of the object.

Think of a red fi re engine When sunlight shines on

the fi re engine, the fi re engine absorbs all colors of light

except red The fi re engine refl ects the red light

What colors do these different objects refl ect?

13

An object looks like the color of the light it refl ects

If an object refl ects all colors of light, it will look white

to your eye If an object absorbs all colors of light, it will look black to your eye

Have you ever seen a stained glass window? You can see some of the colors in sunlight through the window

Each pane of glass is a different color So each pane only lets one color in sunlight go through The rest is absorbed All of these colors are in sunlight! Passing sunlight through stained glass can create light sources of different colors

Colors of Light

Sunlight is made of all colors of light Some lightbulbs

make only one color of light What happens if a colored

light shines on an object?

The color of light that hits an object can change the

color of the object Look at the picture of the fountain

When red light strikes the water, the water refl ects red

light When yellow light strikes the water, the water

refl ects yellow light

The color of the water changes depending

on the color that is shining on it.

When white light hits the colored cups in the picture below, the yellow cup, for instance, looks yellow But what happens if the cups are in colored light? In blue light, the red cup absorbs the blue light The cup looks black The other cups refl ect blue light These cups look blue In red light, the green and blue cups absorb the red light The cups look dark gray The other cups refl ect the red light They look red You can see that different colors

of light have different effects on objects

The green, yellow, red, and blue cups will appear to have those colors in white light The colors of the cups can change when different colors of light shine on them.

15

absorb take in light

color a property of an object determined by

the light that refl ects from the object

eye the part of the body that is sensitive to

light energy

light a form of energy that that can be seen

and that travels in a straight line away from its source

mirror a surface made of shiny material

opaque describes materials that block light

refl ect bounce off, as a light wave does from

an object

shadow an area that does not receive light

directly

1 Why can’t you see an object being blocked by

something opaque?

2 Why can you see the image of an object clearly in a

mirror?

3 Sunlight hits a yellow beach ball What light does the

ball absorb? What light does it refl ect?

research the eye Write a paragraph about how the eye works What are the parts of the eye? How do they work together to help you see?

on a table with a rough surface?