Chapter 22
The Electromagnetic Spectrum
Study Guide
1.
What is an electromagnetic wave? (p. 564)
A transverse wave, made of electric and magnetic energy, that does not require a medium to travel.
2.
Draw a diagram of an electromagnetic wave. Label the two types of energy that make up EM waves. Explain why EM waves are considered to be transverse waves.
(p. 564)
It is considered transverse because the two energies are perpendicular to one another.
3.
Name a type of light that isn’t visible to humans. (p. 567) radio waves, microwaves, infrared waves, ultraviolet waves, x-rays and gamma rays are all invisible to humans. only visible light, in the middle of the spectrum, is visible to humans
4.
What is the electromagnetic spectrum?
All of the different types of electromagnetic waves put together, in order of wavelength, is called the electromagnetic spectrum. at one end, is the longest wavelength waves (radio waves) and at the other end are the waves with the shortest wavelength (gamma rays)
5.
List the seven different types of EM waves, from lowest frequency to highest frequency. (p. 568) radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays
6.
What is special about the wavelength of radio waves?
They have the longest wavelengths of all the EM waves

7.
What are radio waves used for? (p. 568 and 570) sending radio and television signals and for cell phone signals
8.
Do microwaves carry more or less energy than radio waves? (p. 570) more energy, because they have a higher frequency
9.
Name two things that microwaves are used for. (p. 570 & 571)
For cooking food in microwave ovens; radar guns police officers use to track speeding cars. Also, the newer cell phones use microwaves.
10.
What do infrared waves do? (p. 571)
Infrared waves cause heat. We feel the heat of the sun because of infrared waves.
11.
How can we “see” (detect) infrared waves? (p. 571) night vision cameras can detect infrared waves
12.
Is visible light a large or small part of the electromagnetic spectrum? (p. 572) a very narrow sliver in the middle section of the EM spectrum
13.
What does “Roy G. Biv” mean? (p. 572) red, orange, yellow, green, blue, indigo, and violet – the colors of the rainbow
14.
List the colors of visible light, in order, from the smallest wavelength to the largest wavelength. (p. 572) violet, indigo, blue, green, yellow, orange and red – red has the longest wavelength, while
“violent violet” has the smallest (the highest frequency, the most energy)

15.
What is ultraviolet light? (p. 573) another type of EM wave, with a greater frequency than visible light; it can cause you to tan, but can also cause skin cancer—so wear your sunscreen!
16.
X-rays have very short wavelengths. How do we use these to help humans? (p. 574)
X-rays can be used to take pictures of the insides of our bodies to see if we have broken bones.
17.
Can X-rays be harmful? (p. 574)
Yes, too much exposure can cause cancers.
18.
What are some negative effects of gamma rays? What are some positive effects? (p.
574)
Positive:
Negative:
 can be used to treat certain forms of cancer
 can kill healthy cells
 nuclear weapons release gamma rays and cause radiation poisoning
19.
Which type of EM wave has the shortest wavelength? (p. 574)
Gamma rays
20.
Which type of EM wave has the highest amount of energy?
Gamma rays, because they have the highest frequency.

4 Hz

The bending of a wave, as it passes through a different medium.
It is responsible for pencils looking broken when they are placed in a glass of water.
25.
Draw a diagram that shows how refraction is responsible for us being able to see the colors in the rainbow when light passes through a prism. (p. 578)
26.
When light strikes any form of matter, it can interact with the matter in three different ways. What are those three ways? (p. 581) it can be transmitted, reflected or absorbed
27.
What is the transmission of light? (p. 581) the passing of light through matter
28.
What does it mean when we say that matter is transparent? Give an example. (p.
582)
Matter in which light is easily transmitted. A completely clear glass is transparent.

29.
What does it mean when we say that matter is translucent? Give an example. (p.
582)
Matter through which light is transmitted, but the light is blurry.
Wax paper, or our bins in science class are translucent.
30.
What does it mean when we say that matter is opaque? Give an example. (p.
582)
Matter that doesn’t let light energy pass through. Red plastic cups are opaque.
31.
What does it mean when light is absorbed by matter? when the energy of light waves is taken in by matter it comes in contact with
This radiometer spins because light energy is absorbed by the black “paddles”, and “pushes” them.
32.
Explain how absorption is responsible for the fact that you can’t see five miles down the road using a flashlight. (p. 576)
Light energy from the flashlight is absorbed by the air particles it encounters as it moves across the space. The energy then isn’t available to make light.
33.
What happens when visible light is reflected? (p. 575) it bounces off an object

34.
What is the Law of Reflection? Draw a diagram illustrating it. (p. 575)
If you draw an imaginary line from the surface of the mirror straight up to make it perpendicular,

the angle formed by that line and the line made by the incoming light is called the angle of incidence. The angle made by the imaginary perpendicular line and the REFLECTED line is called the angle of reflection and will be equal to the angle of incidence.
35.
What is the difference between regular reflection and diffuse reflection? Draw two diagrams – one of regular reflection and one of diffuse reflection – and use them to explain the difference. (p. 576)
In diffuse reflection, the waves hit, but since the surface is uneven, they bounce back at lots of different angles. In regular reflection, they all bounce back together, because the surface is smooth, so you see a clear reflection of yourself.
36.
Why do we see red when we look at a strawberry? Draw a picture of a strawberry and the wave the waves behave, to help you explain. (p. 582-583)
The red of the strawberry absorbs all of the colors of the rainbow EXCEPT red. We see the color that is reflected. red light reflected orange, yellow, green, blue, indigo and violet are absorbed.

37.
If we combine all the colors of LIGHT ENERGY together, what color light will we get? white light
38.
What are the primary colors of light?
Blue, green and red. Together, at the right amplitudes, they produce white light.
39.
When we see black, what has happened?
The light of all of the colors of the rainbow are being absorbed by the material, so nothing is being reflected back. This is the reason that clothing manufacturers make most summer clothes in whites and light colors, and more winter clothes in black and dark colors. Because white clothes reflect back most of the light (and heat!) energy, since they reflect back all of the colors of light; black clothes absorb all of the colors of light (and the heat), so they take in more energy from the sun.
Diffraction is the bending of a wave around a barrier or through an opening.
Light waves don’t diffract easily, unlike sound waves. That’s why you can hear someone talking around the corner, but can’t see them. The sound waves bend more.