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Chapter 24 | Electromagnetic Waves 1113
problem to your friend, who is also skipping around on the moon: yelling or flashing a light? Why?
5. Given the waveform in Figure 24.5(d), if
and , which of the
following is the correct equation for the wave at the antenna? a.
b.
c.
d.
6. Given the waveform in Figure 24.5(d), if GHz
and , what is the correct equation for the magnetic field wave at the antenna?
7. In Heinrich Hertz’s spark gap experiment (Figure 24.4), how will the induced sparks in Loop 2 compare to those created in Loop 1?
a. Stronger
b. Weaker
c. Need to know the tuner settings to tell
d. Weaker, but how much depends on the tuner settings.
8. The sun is far away from the Earth, and the intervening space is very close to empty. Yet the tilt of the Earth’s axis of rotation relative to the sun results in seasons. Explain why, given what you have learned in this section.
24.3 The Electromagnetic Spectrum
9. The correct ordering from least to greatest wavelength is:
a. ELF, FM radio, microwaves, infrared, red, green,
ultraviolet, x-ray, gamma ray
b. ELF, FM radio, microwaves, infrared, green, red,
ultraviolet, x-ray, gamma ray
c. gamma ray, x-ray, ultraviolet, red, green, infrared,
microwaves, FM radio, ELF
d. gamma ray, x-ray, ultraviolet, green, red, infrared,
microwaves, FM radio, ELF
10. Describe how our vision would be different if we could see energy in what we define as the radio spectrum.
24.4 Energy in Electromagnetic Waves
11. An old microwave oven outputs only half the electric field it used to. How much longer does it take to cook things in this microwave oven?
a. Four times as long
b. Twice as long
c. Half the time
d. One fourth the time
12. Describe at least two improvements you could make to a radar set to make it more sensitive (able to detect things at longer ranges). Explain why these would work.
