887
Chapter 22 Electromagnetic waves
CHAPTER 22 PROBLEMS 5, [6]
5.
Strategy and Solution
At a point due south of the transmitter, the EM waves are traveling due south. The electric
field at this point is oriented vertically, like the antenna. The magnetic field is perpendicular to both the electric
field and the direction the EM waves travel, so the magnetic field must be oriented east-west.
6.
Strategy and Solution
At a point due north of the transmitter, the EM waves are traveling due north. The electric
field at this point is oriented vertically, like the antenna. A receiver should be oriented the same as the transmitter,
so the orientation of the receiver should be vertical.
CHAPTER 22 PROBLEMS: [12], [15], 17, 19, 27, 32
12. Strategy
The frequency, wavelength, and speed of EM radiation are related by
.
f
c
λ
=
Solution
Compute the wavelength of the radio waves.
8
6
3.00
10 m s
3.3 m
90.9
10
Hz
c
f
λ
×
=
=
=
×
15. Strategy
The speed of light in matter is given by
,
v
c n
=
where
n
is the index of refraction.
Solution
Compute the index of refraction of topaz.
8
8
3.00
10 m s
1.62
1.85
10 m s
c
n
v
×
=
=
=
×
17. Strategy
The time of travel is equal to the distance traveled divided by the rate of travel.
Solution
Compute the time it takes for light to travel 50.0 cm.
2
9
8
50.0
10
m
1.67
10
s
1.67 ns
3.00
10 m s
d
t
c
−
−
×
Δ =
=
=
×
=
×
19. (a) Strategy
The wavelength is shorter in matter than it is in vacuum. Use Eq. (22-5).
Solution
Compute the wavelength of light inside the glass.
v
g
692 nm
455 nm
1.52
n
λ
λ
=
=
=
(b)
Strategy
The frequency in glass is the same as the frequency in air. Use
.
c
f
λ
=
Solution
Compute the frequency of light inside the glass.
8
14
g
a
9
a
3.00
10 m s
4.34
10
Hz
692
10
m
c
f
f
λ
−
×
=
=
=
=
×
×
27. Strategy
The electric and magnetic fields oscillate with the same frequency, and their amplitudes are proportional
to each other. Use Eq. (22-6).

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