1. Q32.1
Maxwell’s equations are shown here for a region of space with no charges and no conduction currents. Complete the sentence: “The _______ equation describes how a time-varying electric field generates a magnetic field, and the _______ equation describes how a time-varying magnetic field generates an electric field.”
first, second
first, third
second, first
third, fourth
fourth, third
Answer: E

2. A32.1
Maxwell’s equations are shown here for a region of space with no charges and no conduction currents. Complete the sentence: “The _______ equation describes how a time-varying electric field generates a magnetic field, and the _______ equation describes how a time-varying magnetic field generates an electric field.”
first, second
first, third
second, first
third, fourth
fourth, third

3. Q32.2
Maxwell’s equations are shown for here a region of space with no charges and no conduction currents. Complete the sentence: “For an electromagnetic wave in vacuum, the _______ equation explains why the electric field is transverse, and the _______ equation explains why the magnetic field is transverse.”
first, second
first, third
second, first
third, fourth
fourth, third
Answer: A

4. A32.2
Maxwell’s equations are shown for here a region of space with no charges and no conduction currents. Complete the sentence: “For an electromagnetic wave in vacuum, the _______ equation explains why the electric field is transverse, and the _______ equation explains why the magnetic field is transverse.”
first, second
first, third
second, first
third, fourth
fourth, third

5. has higher frequency and travels faster than the violet light.
In a vacuum, one color of red light has a wavelength of 700 nm and one color of violet light has a wavelength of 400 nm. This means that in a vacuum, the red light
has higher frequency and travels faster than the violet light.
has higher frequency and travels slower than the violet light.
has lower frequency and travels faster than the violet light.
has lower frequency and travels slower than the violet light.
matches none of the above answers.
Answer: E

6. A32.3
In a vacuum, one color of red light has a wavelength of 700 nm and one color of violet light has a wavelength of 400 nm. This means that in a vacuum, the red light
has higher frequency and travels faster than the violet light.
has higher frequency and travels slower than the violet light.
has lower frequency and travels faster than the violet light.
has lower frequency and travels slower than the violet light.
matches none of the above answers.

7. This wave is propagating in the
Q32.4
At a certain point in space, the electric and magnetic fields of an electromagnetic wave at a certain instant are given by
This wave is propagating in the
positive x-direction.
negative x-direction.
positive y-direction.
negative y-direction.
unknown direction.
Answer: D

8. A32.4
At a certain point in space, the electric and magnetic fields of an electromagnetic wave at a certain instant are given by
This wave is propagating in the
positive x-direction.
negative x-direction.
positive y-direction.
negative y-direction.
unknown direction.

9. Q32.5
A sinusoidal electromagnetic wave in a vacuum is propagating in the positive z-direction. At a certain point in the wave at a certain instant in time, the electric field points in the negative x-direction. At the same point and at the same instant, the magnetic field points in the
positive y-direction.
negative y-direction.
positive z-direction.
negative z-direction.
unknown direction.
Answer: B

10. A32.5
A sinusoidal electromagnetic wave in a vacuum is propagating in the positive z-direction. At a certain point in the wave at a certain instant in time, the electric field points in the negative x-direction. At the same point and at the same instant, the magnetic field points in the
positive y-direction.
negative y-direction.
positive z-direction.
negative z-direction.
unknown direction.

11. This wave propagates in the
Q32.6
In a sinusoidal electromagnetic wave in a vacuum, the electric field has only an x-component. This component is given by
This wave propagates in the
positive z-direction.
negative z-direction.
positive y-direction.
negative y-direction.
unknown direction.
Answer: D

12. A32.6
In a sinusoidal electromagnetic wave in a vacuum, the electric field has only an x-component. This component is given by
This wave propagates in the
positive z-direction.
negative z-direction.
positive y-direction.
negative y-direction.
unknown direction.

13. The magnetic field of this wave
Q32.7
In a sinusoidal electromagnetic wave in a vacuum, the electric field has only an x-component. This component is given by
The magnetic field of this wave
A. has only an x-component.
B. has only a y-component.
C. has only a z-component.
D. has components along two of the x-, y-, and z-axes.
E. not enough information is given to decide.
Answer: C

14. A32.7
In a sinusoidal electromagnetic wave in a vacuum, the electric field has only an x-component. This component is given by
The magnetic field of this wave
A. has only an x-component.
B. has only a y-component.
C. has only a z-component.
D. has components along two of the x-, y-, and z-axes.
E. not enough information is given to decide.

15. A. is the same at all points in the wave.
Q32.8
In a sinusoidal, traveling electromagnetic wave in a vacuum, the magnetic energy density
A. is the same at all points in the wave.
B. is maximum where the electric field has its greatest value.
C. is maximum where the electric field is zero.
D. is negative where the electric energy density is positive.
E. More than one of the above is true.
Answer: B

16. A32.8
In a sinusoidal, traveling electromagnetic wave in a vacuum, the magnetic energy density
A. is the same at all points in the wave.
B. is maximum where the electric field has its greatest value.
C. is maximum where the electric field is zero.
D. is negative where the electric energy density is positive.
E. More than one of the above is true.

17. Q32.9
The drawing shows a sinusoidal electromagnetic wave in a vacuum at one instant of time at points between x = 0 and At this instant, at which of the values of x in the drawing does the instantaneous Poynting vector have its maximum magnitude?
Answer: D

18. A32.9
The drawing shows a sinusoidal electromagnetic wave in a vacuum at one instant of time at points between x = 0 and At this instant, at which of the values of x in the drawing does the instantaneous Poynting vector have its maximum magnitude?

19. A. points along the x-axis. B. points along the y-axis.
Q32.10
The drawing shows a sinusoidal electromagnetic standing wave. The average Poynting vector in this wave
A. points along the x-axis.
B. points along the y-axis.
C. points along the z-axis.
D. is zero.
E. exhibits none of the above.
Answer: D

20. A32.10
The drawing shows a sinusoidal electromagnetic standing wave. The average Poynting vector in this wave
A. points along the x-axis.
B. points along the y-axis.
C. points along the z-axis.
D. is zero.
E. exhibits none of the above.

21. Wavelength = 550 nm, magnetic field amplitude
Q-RT32.1
The following are properties of three different sinusoidal, traveling electromagnetic plane waves. Rank the waves in order from highest to lowest intensity.
Wavelength = 550 nm, magnetic field amplitude
Wavelength = 1.20 µm, electric field amplitude = 600 V/m
Wavelength = 2.00 cm, average energy density of wave
Answer: BAC

22. A-RT32.1
The following are properties of three different sinusoidal, traveling electromagnetic plane waves. Rank the waves in order from highest to lowest intensity.
Wavelength = 550 nm, magnetic field amplitude
Wavelength = 1.20 µm, electric field amplitude = 600 V/m
Wavelength = 2.00 cm, average energy density of wave
Answer: BAC