Chapter 8: Electromagnetism and EM Waves
MULTIPLE CHOICE
1. The deviation from the way a compass needle points from the true north direction is the
a. greenhouse effect
b. magnetic inclination
c. magnetic declination
d. magnetic resonance effect
e. none of the above
2. The direction of a magnetic field at a point can be determined by
a. a generator
b. a compass
c. a transformer
d. electromagnetic induction
e. none of the above
3. A magnetic field exerts a force on an electric charge if the charge is
a. positive
b. negative
c. moving
d. stationary
e. any of the above
4. A magnetic field is created by an electric charge if the charge is
a. positive
b. negative
c. moving
d. stationary
e. any of the above
7. The ionosphere
a. reflects all EM waves
b. reflects high frequency radio waves
c. reflects low frequency radio waves
d. is responsible for the greenhouse effect
e. absorbs ultraviolet light in sunlight
8. The ozone layer
a. reflects all EM waves
b. reflects high frequency radio waves
c. reflects low frequency radio waves
d. is responsible for the greenhouse effect
e. absorbs ultraviolet light in sunlight
9. The greenhouse effect occurs because
a. low frequency EM waves are reflected from the atmosphere
b. high frequency EM waves are reflected from the atmosphere
c. the ozone layer absorbs ultraviolet light
d. carbon dioxide in the atmosphere absorbs infrared radiation
e. none of the above
10. The greenhouse effect is occurring because
a. the ozone layer is being depleted
b. the amount of carbon dioxide in the atmosphere is increasing
c. the ionosphere reflects low frequency radiation
d. more ultraviolet radiation is penetrating the atmosphere
e. none of the above
12. A superconductor expels any magnetic field from its interior. This is called
a. electromagnetic induction
b. Maxwell’s effect
c. magnetic declination
d. the Meissner effect
e. none of the above
13. The main form of radiation that our bodies emit is
a. ultraviolet
b. infrared
c. x ray
d. microwave
e. blackbody
14. The radiation emitted from a small hole in a furnace is
a. ultraviolet
b. infrared
c. x ray
d. microwave
e. blackbody
15. The type of EM waves used in radar is
a. ultraviolet
b. infrared
c. x ray
d. microwave
e. blackbody
16. The type of EM wave having the highest frequency is
a. ultraviolet
b. infrared
c. x rays
d. microwave
e. gamma rays
17. The EM wave that has the lowest frequency in this list is
a. ultraviolet
b. infrared
c. x rays
d. microwave
e. gamma rays
18. The lowest frequency visible light is
a. violet
b. red
c. blue
d. green
e. yellow
19. The highest frequency visible light is
a. violet
b. red
c. blue
d. green
e. yellow
20. Which of the following is not a common use of microwaves?
a. cooking
c. radar
b. medical imaging
d. communications
21. How do microwave ovens can heat food more quickly than conventional ovens?
a. Microwaves give energy directly to the molecules in the food.
b. Conventional ovens must conduct heat from the surface to the interior of the food.
c. Microwaves heat the inside as well as the surface of the food.
d. all of the above
22. The EM wave that has the smallest wavelength in this list is
a. ultraviolet
b. infrared
c. x rays
d. microwave
e. gamma rays
23. The type of EM radiation that causes your skin to tan is
a. ultraviolet
b. infrared
c. x rays
d. microwave
e. gamma rays
24. FM radio only operates in the frequency range 88 MHz to 108 MHz because
a. higher or lower frequencies are blocked by the ionosphere
b. higher and lower frequencies are not radio waves
c. the government set those limits
d. none of the above
25. Why would a decrease in the amount of ozone in the atmosphere increase the likelihood of
people getting sunburn?
a.
b.
c.
d.
Global temperatures would rise
More ultraviolet radiation would reach the ground
People would be exposed to more infrared radiation
The premise is incorrect. Ozone and sunburn are not related
26. The type of EM radiation emitted when high speed electrons decelerate as they are smashed
into a metal target is
a. ultraviolet
b. infrared
c. x ray
d. microwave
e. gamma ray
27. The type of EM radiation that has wavelength just a bit shorter than that of visible light is
a. ultraviolet
b. infrared
c. x ray
d. microwave
e. gamma ray
28. The type of EM radiation that has wavelength just a bit longer than that of visible light is
a. ultraviolet
b. infrared
c. x ray
d. microwave
e. gamma ray
30. AM radio stations have greater range than FM stations because
a. AM is more efficient than FM
b. they have more powerful transmitters
c. their lower frequency radio waves reflect off the ionosphere
d. none of the above
32. Global warming
a. has not yet been observed
b. has been caused by increasing levels of carbon dioxide in the atmosphere
c. has led to a depletion of the ozone layer in the atmosphere
d. has no serious consequences
For a body emitting blackbody radiation, the total power emitted is proportional to the 4th
power of the body’s absolute temperature:
(T in kelvins)
and the wavelength of the emitted EM radiation that has the highest intensity is inversely
proportional to the body’s absolute temperature according to:
(
in meters, T in kelvins)
Assume an object is emitting blackbody radiation.
33. If the Kelvin temperature of an object is doubled, the amount of radiant energy emitted each
second is ____________ the original amount.
a. 1/16th
b. half
c. the same as
d. 2 times
e. 16 times
34. As the temperature of an object increases, the wavelength of the brightest light emitted
a. increases
b. decreases
c. doesn’t change
d. depends on the composition of the body
e. depends on the size of the body
35. If the Kelvin temperature of a body is doubled, the wavelength of the most intense light is
____________ the wavelength originally of the most intense light.
a. 1/16th
b. half
c. the same as
d. 2 times
e. 16 times
36. As the temperature of a body increases,
a. the body gets brighter
b. the color of the body shifts from red to white
c. the wavelength of the most intense light decreases
d. the frequency of the most intense light increases
e. all the above
37. A body in a room at 300 K is heated to 3,000 K. The amount of energy radiated each second
by the body increases by a factor of
a. 10
b. 100
c. 1,000
d. 10,000
e. 100,000
38. A body in a room at 300 K is heated to 3,000 K. The wavelength of the most intense EM
radiation emitted by the body at 3,000 K is the wavelength of the most intense EM radiation at
300 K.
a. 0.0001 times
b. 0.1 times
c. the same as
d. 10 times
e. 10,000 times
39. About how hot does something have to get to glow red hot?
a. 375 degrees F
c. 3000 K
b. 800 degrees F
d. 6000 K
42. What does “IR” stand for?
a. ultraviolet
b. muon neutrino
c. high frequency
d. infrared
45. A current can be made to flow in a wire if
a. it is connected to a battery
c. a magnet is put into motion near it
b. it is put into motion near a magnet
d. all of the above
46. Making a digital recording of a sound involves
a. analog-to-digital conversion
c. electromagnetic waves
b. digital-to-analog conversion
d. all of the above