Light

Copyright © by Holt, Rinehart and Winston. All rights reserved.

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How to Use This Presentation



Resources

Chapter Presentation

Image Bank

Math Focus

Bellringers

Standards Assessment

Visual Concepts



Chapter 3 Light and Living Things

Table of Contents

Section 1 The Electromagnetic Spectrum

Section 2 Interactions of Light with Matter

Section 3 Refraction



Section 1 The Electromagnetic Spectrum Chapter 3

Bellringer

Describe the weather conditions necessary to produce a rainbow.

Why do you think rainbows form?

Write your responses in your science journal.



Chapter 3

What You Will Learn

• Light is an electromagnetic wave

• Visible light is a small part of a very broad electromagnetic spectrum.

• White light is a mixture of many wavelengths of visible light.

• Infrared waves and ultraviolet light affect living things.




Chapter 3

• Visible light, infrared waves, and ultraviolet light are small parts of a large electromagnetic spectrum.

• An electromagnetic wave (EM wave) is a wave that consists of changing electric and magnetic fields.

• Light is an electromagnetic wave.




Chapter 3

Light: An Electromagnetic Wave, continued

• EM waves can travel through matter, like sound waves or water waves.




Light and Living Things

Electromagnetic Waves

Chapter 3

QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.



Chapter 3

A Spectrum of Waves

• The entire range of electromagnetic waves is called the electromagnetic spectrum.

• Visible light, ultraviolet light, and infrared waves are portions of the EM spectrum that are important to living things.

• Other EM waves in the EM spectrum include radio waves and X-rays.




Section 1 The Electromagnetic Spectrum Chapter 3



Chapter 3

A Spectrum of Waves, continued

• The different types of EM waves are distinguished by their wavelengths.

• A wavelength is the distance from any point on a wave to an identical point on the next wave.




Chapter 3

Infrared Waves

• Warmer objects give off more infrared waves than cooler objects do.

• Infrared waves from the sun keep the temperatures on Earth suitable for life. It’s the heat you feel from the sun.

• Slower wavelengths than visible light.




Chapter 3

Visible Light

• Visible light is the very narrow range of wavelengths in the EM spectrum that humans can see.




Chapter 3

• Visible light from the sun is white light. White light is the combination of all of the visible wavelengths of light.

• Cells in the human eye react to different wavelengths. This difference is perceived as the different colors.

• The longest wavelengths are seen as red light. The shortest wavelengths are seen as violet light.


Visible Light, continued



Chapter 3

Visible Light, continued

• The range of colors is called the visible spectrum, and can be remembered with the name ROY G. BiV (red, orange, yellow, green, blue, indigo, violet).




Chapter 3

Ultraviolet Light

• Ultraviolet light has shorter wavelengths than visible light.

• Ultraviolet light affects your body in both bad and good ways.

• Ultraviolet light can cause sunburn, skin cancer, wrinkles, and damage to the eyes.




Chapter 3

Ultraviolet Light, continued

• On the good side, skin cells produce vitamin D when exposed to ultraviolet light. Vitamin D helps the intestines absorb calcium.

• Special ultraviolet lamps are used to kill bacteria on food and surgical tools.




Section 2 Interactions of Light with MatterChapter 3

Bellringer

How do mirrors work?

What do mirrors do to light waves?

Write your answers in your science journal.



Chapter 3

What You Will Learn

• Light travels in straight lines if the material that the light travels through does not change.

• The angle of reflection of a light beam is equal to the angle of incidence.

• An object can be seen if light emitted by or reflected by it is detected by the eye.

• Light can be reflected, absorbed, scattered, or transmitted by matter.




Chapter 3

Reflection

• Light interacts with matter during reflection, absorption, scattering, and transmission.

• Light travels in a straight line unless the material it is traveling through changes. One way to change the direction of light is by reflection.

• Reflection is the bouncing back of light rays when they hit an object.




Chapter 3

• The law of reflection states that the angle of incidence is equal to the angle of reflection.

• This means light will bounce off an object at the same angle it strikes the object.


Reflection, continued



Chapter 3

• Light bouncing off a mirror is an an example of regular reflection.

• When light strikes a rougher surface, such as a wall, the light is bounced in many directions. This type of reflection is called diffuse reflection.

• You can see your image in the regular reflection of a mirror but not in the diffuse reflection of a wall.


Reflection, continued









Chapter 3

Light and Matter

• Light interacts with all matter in one or more of the following ways: reflection, absorption, and transmission.

• Reflections allows you to see objects. Absorption can cause objects to feel warmer as energy is transferred from the light.

• Transmission is the passing of light through matter.




Chapter 3

Light and Matter, continued

• Light is transmitted easily through transparent matter. Air, glass, and water that are pure are transparent.

• Light is transmitted through but also scattered by translucent matter. Frosted glass and wax paper are translucent.

• Matter that does not transmit any light is opaque. You cannot see through opaque matter.





Click below to watch the Visual Concept.

You may stop the video at any time by pressing the Esc key.

Visual Concept

Opaque, Translucent, Transparent

Chapter 3



Chapter 3

Colors and Objects

• When white light strikes a colored opaque object, some wavelengths (colors) are absorbed, and some are reflected.

• You see only the colors (wavelengths) that are reflected. A berry looks red because it reflects red light and absorbs the other colors of light.

• Black objects absorb all colors of light, and white objects reflect all colors of light.




Color Movie

QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.



Chapter 3

Pigments and Color

• A pigment is a material that gives a substance its color by absorbing some colors of light and reflecting others.




How we see color…



Section 3 RefractionChapter 3

Bellringer

Can light bend?

What happens when light passes through water?

Write your responses in your science journal.



Chapter 3

What You Will Learn

• Light is refracted when the medium it travels in changes.

• Convex and concave lenses refract light to form images.

• Human eyes, magnifying glasses, cameras, telescopes, and microscopes have lenses that form images.




Chapter 3

Refraction and Media

• Light can be bent, or refracted, by matter. Lenses refract light to form images.

• Refraction is the bending of a wave as it passes at an angle from one medium to another.

• A medium (plural, media) is a substance through which a wave can travel. Air, water, and glass are three media.




Chapter 3

• Light can also be refracted when the density of a medium changes.

• For example, the density of air above a hot road is less than the surrounding air. This makes objects seem to shimmer or wobble due to refraction.

• Refraction can cause optical illusions, because our brains assume the light is traveling in a straight line.


Refraction and Media, continued



Chapter 3 Section 3 Refraction




Chapter 3


• When white light is refracted, the shorter wave lengths bend more than the longer wavelengths.

Rainbows occur when sunlight is refracted by raindrops.




Chapter 3

Lenses and Refraction of Light

• A lens is a transparent object that forms an image by refracting light.

• A lens that is thicker in the middle than at the edges is a convex lens.

• Convex lenses refract light rays toward each other. The point at which the light rays cross is called the focal point.




Chapter 3

• The lens of the human eye is a convex lens. It focuses light on the retina at the back of the eye.

• A magnifying glass is also a convex lens.

• Depending on how close a convex lens is to an object, it can form an image that is larger or smaller than the object.


Lenses and Refraction of Light, continued



Chapter 3

Lenses and Refraction of Light, continued

• Like humans, many animal eyes also contain convex lenses.

• Concave lenses are thinner in the middle than at the edges. They only form virtual images, which are always smaller than the object.

• Concave lenses cause light rays to refract away from each other.





Click below to watch the Visual Concept.

You may stop the video at any time by pressing the Esc key.

Visual Concept

Comparing Real and Virtual Images

Chapter 3



Chapter 3

Optical Instruments and Refraction

• Optical instruments can help you make observations of objects that are very small or very far away.

• Many contain both concave and convex lenses.

• The way a camera works is similar to the way your eye works. Light enters the lens and is focused at the back of the camera.










Chapter 3

• Telescopes are used to see images of large, distant objects. A telescope that uses lenses to focus light is called a refracting telescope.

• A simple refracting telescope has two convex lenses. The objective lens is pointed at the object, and an eyepiece lens, or ocular, magnifies the image.


Optical Instruments and Refraction, continued



Chapter 3

Optical Instruments and Refraction, continued

• A light microscope is similar to a refracting telescope, with lenses configured to magnify small, close objects.










Chapter 3 Light and Living Things

Use the terms below to complete the concept map on the next slide.

absorption

reflection

matter

energy

light

refraction

transmission

Concept Map



Light and Living ThingsChapter 3

Concept Map



Light and Living ThingsChapter 3

Concept Map



Light and Living Things Chapter 3

End of Chapter 3 Show



Chapter 3 Standards Assessment

1. Which of the following words means “that can be seen,”?

A. visible

B. audible

C. palpable

D. sensible




1. Which of the following words means “that can be seen,”?

A. visible

B. audible

C. palpable

D. sensible




2. Which of the following sets of words best completes the following sentence: Light is ____ the eye.

A. detects with

B. detected for

C. detected by

D. detecting in




2. Which of the following sets of words best completes the following sentence: Light is ____ the eye.

A. detects with

B. detected for

C. detected by

D. detecting in




3. Which of the following sets of words best completes the following sentence: Light can be ____ matter.

A. transmitted with

B. transmits in

C. transmits by

D. transmitted through




3. Which of the following sets of words best completes the following sentence: Light can be ____ matter.

A. transmitted with

B. transmits in

C. transmits by

D. transmitted through




4. Which of the following words is closest in meaning to the word react?

A. repeat

B. renovate

C. respond

D. remove




4. Which of the following words is closest in meaning to the word react?

A. repeat

B. renovate

C. respond

D. remove




5. Which of the following best describes the relationship between infrared waves, ultraviolet light, and visible light?

A. Infrared waves are found on the electromagnetic spectrum, while ultraviolet and visible light are not.

B. Infrared waves have the longest wavelength, followed by visible light and ultraviolet light.

C. Infrared waves and visible light are visible to the human eye, while ultraviolet light is not.

D. Infrared waves consist of changing electric and magnetic fields, while ultraviolet light and visible

light do not.




5. Which of the following best describes the relationship between infrared waves, ultraviolet light, and visible light?

A. Infrared waves are found on the electromagnetic spectrum, while ultraviolet and visible light are not.

B. Infrared waves have the longest wavelength, followed by visible light and ultraviolet light.

C. Infrared waves and visible light are visible to the human eye, while ultraviolet light is not.

D. Infrared waves consist of changing electric and magnetic fields, while ultraviolet light and visible

light do not.




6. Your eyes detect a burning candle in a candleholder. Your eyes see the candle flame because it emits light. Why do your eyes see the opaque candleholder?

A. It is luminous.

B. It is illuminated.

C. It absorbs light.

D. It transmits light.




6. Your eyes detect a burning candle in a candleholder. Your eyes see the candle flame because it emits light. Why do your eyes see the opaque candleholder?

A. It is luminous.

B. It is illuminated.

C. It absorbs light.

D. It transmits light.




7. Use the image below to answer the following question.




7. The diagrams on the previous slide show how light interacts with two different surfaces. Which of the following statements is true?

A. Diagram A illustrates the process of diffuse reflection.

B. You will be able to see your reflection in surface B but not in Surface A.

C. Diagram B illustrates the process of regular reflection.

D. You will be able to see your reflection in surface A but not in surface B.




7. The diagrams on the previous slide show how light interacts with two different surfaces. Which of the following statements is true?

A. Diagram A illustrates the process of diffuse reflection.

B. You will be able to see your reflection in surface B but not in Surface A.

C. Diagram B illustrates the process of regular reflection.

D. You will be able to see your reflection in surface A but not in surface B.




8. The diagram above illustrates the law of reflection. What is found at point E in the diagram?

A. the angle of incidence

B. the angel of reflection

C. the incident beam

D. the reflected beam




8. The diagram above illustrates the law of reflection. What is found at point E in the diagram?

A. the angle of incidence

B. the angel of reflection

C. the incident beam

D. the reflected beam




9. What happens to white light during refraction?

A. It appears to be closer than it actually is.

B. It absorbs the pigment of the medium it passes through.

C. It separates into different wavelengths or colors.

D. It is refracted at the same angle as the angle of incidence.




9. What happens to white light during refraction?

A. It appears to be closer than it actually is.

B. It absorbs the pigment of the medium it passes through.

C. It separates into different wavelengths or colors.

D. It is refracted at the same angle as the angle of incidence.




10. What part of a camera is most like the retina in the human eye?

A. the lens

B. the film

C. the shutter

D. the aperture




10. What part of a camera is most like the retina in the human eye?

A. the lens

B. the film

C. the shutter

D. the aperture




11. What happens when white light shines through a translucent, red, glass window?

A. All colors of light except red are transmitted through the glass.

B. Red light is transmitted through and reflected

by the glass.

C. Red light is absorbed by the glass.

D. All colors of light except red are reflected by the glass.




11. What happens when white light shines through a translucent, red, glass window?

A. All colors of light except red are transmitted through the glass.

B. Red light is transmitted through and reflected

by the glass.

C. Red light is absorbed by the glass.

D. All colors of light except red are reflected by the glass.




12. While you are conducting an experiment, your lab partner burns himself on a candle flame. After such an accident, you should

A. take your partner to the bathroom and wash the burn with soap.

B. perform first aid by rinsing the burned area with warm water.

C. tell your teacher, even if the burn seems like a minor injury.

D. continue with your lab and tell no one about what has happened.




12. While you are conducting an experiment, your lab partner burns himself on a candle flame. After such an accident, you should

A. take your partner to the bathroom and wash the burn with soap.

B. perform first aid by rinsing the burned area with warm water.

C. tell your teacher, even if the burn seems like a minor injury.

D. continue with your lab and tell no one about what has happened.




13. Corals and producers live in the neritic zones of an ocean. Whales and squid live in the oceanic zone. Bacteria and worms live in the benthic zone. Which of the following factors most determines the types of organisms that live at each level?A. the strength of underwater currents and daily

tidesB. the amount of fresh water that falls as

precipitationC. the number of predators living in the oceanic

zoneD. the depth to which sunlight can penetrate the

water




13. Corals and producers live in the neritic zones of an ocean. Whales and squid live in the oceanic zone. Bacteria and worms live in the benthic zone. Which of the following factors most determines the types of organisms that live at each level?A. the strength of underwater currents and daily

tidesB. the amount of fresh water that falls as

precipitationC. the number of predators living in the oceanic

zoneD. the depth to which sunlight can penetrate the

water




14. If sunlight could not reach Earth’s surface, which of the following would happen first?

A. Producers would die.

B. Consumers would die.

C. Scavengers would die.

D. Decomposers would die.




14. If sunlight could not reach Earth’s surface, which of the following would happen first?

A. Producers would die.

B. Consumers would die.

C. Scavengers would die.

D. Decomposers would die.



Chapter 3



Chapter 3Section 1 The Electromagnetic

Spectrum



Chapter 3Section 1 The Electromagnetic

Spectrum







Light

Technology

light waves

visible light visible

reflection light

electromagnetic waves

light travels

white light

red light

light beam