Question 1

The speed of an electromagnetic wave in vacuum depends on

Accepted Answer

A)  the amplitude of the electric and magnetic fields. 
B)  the frequency of the wavelength. 
C)  the angle between the electric and magnetic fields. 
D)  none of these choices are correct. 
A)  the amplitude of the electric and magnetic fields. 
B)  the frequency of the wavelength. 
C)  the angle between the electric and magnetic fields. 
D)  none of these choices are correct. D

Question 2

A radio station utilizes a horizontal electric dipole antenna directed north-south as a transmitter. You are located due west of the station and wish to use a magnetic dipole antenna to receive the broadcast. What should the orientation of your antenna be?

Accepted Answer

A)  axis horizontal east-west 
B)  axis horizontal in any direction 
C)  axis horizontal north-south 
D)  Unable to answer given the information. 
E)  axis vertical 
A)  axis horizontal east-west 
B)  axis horizontal in any direction 
C)  axis horizontal north-south 
D)  Unable to answer given the information. 
E)  axis vertical E

Question 3

Light of wavelength 661.1 nm is received from a star that is emitting light of wavelength 659.6 nm. How fast is the star moving relative to the Earth, and is it moving toward or away?

Accepted Answer

A)  580 km/s away 
B)  580 km/s toward 
C)  680 km/s away 
D)  680 km/s toward 
A)  580 km/s away 
B)  580 km/s toward 
C)  680 km/s away 
D)  680 km/s toward C

Question 4

What total power is radiated by a light bulb that provides 12 mW on a 15 cm × 25 cm sheet of paper, which is 1.7 m from the bulb? Assume that the paper is oriented with its surface perpendicular to the light rays.

Accepted Answer

A)  2.9 W 
B)  12 W 
C)  1.7 W 
D)  6.6 W 
A)  2.9 W 
B)  12 W 
C)  1.7 W 
D)  6.6 W

Question 5

What is a light-year in SI units?

Accepted Answer

A)  3.0 × 1015 m 
B)  9.5 × 1015 m 
C)  3.0 × 1011 m 
D)  1.1 × 1011 m 
E)  4.5 × 1037 m 
A)  3.0 × 1015 m 
B)  9.5 × 1015 m 
C)  3.0 × 1011 m 
D)  1.1 × 1011 m 
E)  4.5 × 1037 m

Question 6

Radiation of intensity 1.00 kW/m2 is incident on an area perpendicular to the incoming light. The area is now rotated 20° about an axis perpendicular to the incoming light. What is the resulting power per unit area now reaching the surface?

Accepted Answer

A)  1.00 kW/m2 
B)  0.940 kW/m2 
C)  0.880 kW/m2 
D)  0.800 kW/m2 
E)  0.340 kW/m2 
A)  1.00 kW/m2 
B)  0.940 kW/m2 
C)  0.880 kW/m2 
D)  0.800 kW/m2 
E)  0.340 kW/m2

Question 7

Randomly polarized light of intensity I0 is passed through two polarizers whose transmission axes differ by 45°. What is the intensity of the light that has passed through both polarizers?

Accepted Answer

A)  0.70 I0 
B)  0.50 I0 
C)  0.35 I0 
D)  0.25 I0 
E)  0.00 
A)  0.70 I0 
B)  0.50 I0 
C)  0.35 I0 
D)  0.25 I0 
E)  0.00

Question 8

A circularly polarized EM wave has an electric field magnitude 3.0 mV/m. If the wave passes through a polarizer, what will be the amplitude of the electric field in the transmitted wave?

Accepted Answer

A)  3.0 mV/m 
B)  2.1 mV/m 
C)  1.5 mV/m 
D)  0 
A)  3.0 mV/m 
B)  2.1 mV/m 
C)  1.5 mV/m 
D)  0

Question 9

At the Earth's surface, the intensity of solar radiation is approximately 1000 W/m2. At a latitude of 44.5 degrees north, when the Sun is highest in the sky on the winter solstice, the Sun's rays are incident at an angle of 68.0 degrees from the vertical. What power is incident upon a 1.00 m × 1.50 m window in a vertical, south-facing wall at this time?

Accepted Answer

A)  1390 W 
B)  927 W 
C)  562 W 
D)  375 W 
A)  1390 W 
B)  927 W 
C)  562 W 
D)  375 W

Question 10

When light passes from one medium into another with a different index of refraction, which of the following does or do NOT change?

Accepted Answer

A)  the speed 
B)  the wavelength 
C)  the frequency 
D)  the speed and the wavelength 
E)  the frequency and the wavelength 
A)  the speed 
B)  the wavelength 
C)  the frequency 
D)  the speed and the wavelength 
E)  the frequency and the wavelength

Question 11

A circularly polarized EM wave with intensity I0 is incident on a polarizer. What is the intensity of the transmitted wave?

Accepted Answer

A)  I0 
B)  0.71 I0 
C)  0.5 I0 
D)  0 
A)  I0 
B)  0.71 I0 
C)  0.5 I0 
D)  0

Question 12

In vacuum, the components of an EM wave are Ey = (50 V/m) cos [(5.0 m−1)x + ωt], Ex = 0, and Ez = 0. What is the amplitude of the magnetic field for this wave?

Accepted Answer

A)  5.00 × 10−7 T 
B)  1.67 × 10−7 T 
C)  2.00 × 10−7 T 
D)  1.50 × 10−6 T 
E)  1.33 × 10−6 T 
A)  5.00 × 10−7 T 
B)  1.67 × 10−7 T 
C)  2.00 × 10−7 T 
D)  1.50 × 10−6 T 
E)  1.33 × 10−6 T

Question 13

Light from an astronomical source is found to be shifted to a frequency one percent lower than had the source been at rest. What relative velocity could cause such a shift?

Accepted Answer

A)  3.0 × 107 m/s moving away from the observer 
B)  3.0 × 106 m/s moving away from the observer 
C)  3.0 × 106 m/s moving toward the observer 
D)  1.5 × 106 m/s moving toward the observer 
E)  1.5 × 106 m/s moving away from the observer 
A)  3.0 × 107 m/s moving away from the observer 
B)  3.0 × 106 m/s moving away from the observer 
C)  3.0 × 106 m/s moving toward the observer 
D)  1.5 × 106 m/s moving toward the observer 
E)  1.5 × 106 m/s moving away from the observer

Question 14

Electromagnetic waves of wavelength 1000 nm are classified as

Accepted Answer

A)  radio waves. 
B)  microwaves. 
C)  infrared. 
D)  x-rays. 
E)  gamma rays. 
A)  radio waves. 
B)  microwaves. 
C)  infrared. 
D)  x-rays. 
E)  gamma rays.

Question 15

A dipole radio transmitter has its rod-shaped antenna oriented vertically. At a point due south of the transmitter, the radio waves have their magnetic field

Accepted Answer

A)  oriented in any horizontal direction. 
B)  oriented east-west. 
C)  oriented vertically. 
D)  oriented north-south. 
A)  oriented in any horizontal direction. 
B)  oriented east-west. 
C)  oriented vertically. 
D)  oriented north-south.

Question 16

In vacuum, the components of an EM wave are Ey = (50 V/m) cos [(5.00 m−1)x + ωt], Ex = 0, and Ez = 0. In what direction is this wave moving?

Accepted Answer

A)  positive x-direction 
B)  negative x-direction 
C)  positive y-direction 
D)  negative y-direction 
E)  positive or negative z-direction 
A)  positive x-direction 
B)  negative x-direction 
C)  positive y-direction 
D)  negative y-direction 
E)  positive or negative z-direction

Question 17

If unpolarized light with Erms = 20 V/m is passed through a polarizer, what is the transmitted Erms?

Accepted Answer

A)  20 V/m 
B)  14 V/m 
C)  10 V/m 
D)  7.1 V/m 
E)  5.0 V/m 
A)  20 V/m 
B)  14 V/m 
C)  10 V/m 
D)  7.1 V/m 
E)  5.0 V/m

Question 18

Light passes from medium one (v1) to medium two (v2). If v1 2 then at the boundary

Accepted Answer

A)  f increases, λ decreases. 
B)  f does not change, λ increases. 
C)  f decreases, λ increases. 
D)  f does not change, λ decreases. 
A)  f increases, λ decreases. 
B)  f does not change, λ increases. 
C)  f decreases, λ increases. 
D)  f does not change, λ decreases.

Question 19

If you are facing north with the Sun directly overhead, the light coming to your eyes from the sky just above the horizon is

Accepted Answer

A)  partially polarized east-west. 
B)  partially polarized north-south. 
C)  randomly polarized. 
D)  partially polarized up-down. 
A)  partially polarized east-west. 
B)  partially polarized north-south. 
C)  randomly polarized. 
D)  partially polarized up-down.

Question 20

An electromagnetic wave is created by

Accepted Answer

A)  an electrical charge moving at a certain velocity. 
B)  all electric charges. 
C)  a magnet moving with a certain velocity. 
D)  an accelerating electric charge. 
A)  an electrical charge moving at a certain velocity. 
B)  all electric charges. 
C)  a magnet moving with a certain velocity. 
D)  an accelerating electric charge.

Exam 22: Electromagnetic Waves

The speed of an electromagnetic wave in vacuum depends on

A radio station utilizes a horizontal electric dipole antenna directed north-south as a transmitter. You are located due west of the station and wish to use a magnetic dipole antenna to receive the broadcast. What should the orientation of your antenna be?

Light of wavelength 661.1 nm is received from a star that is emitting light of wavelength 659.6 nm. How fast is the star moving relative to the Earth, and is it moving toward or away?

What total power is radiated by a light bulb that provides 12 mW on a 15 cm × 25 cm sheet of paper, which is 1.7 m from the bulb? Assume that the paper is oriented with its surface perpendicular to the light rays.

What is a light-year in SI units?

Radiation of intensity 1.00 kW/m2 is incident on an area perpendicular to the incoming light. The area is now rotated 20° about an axis perpendicular to the incoming light. What is the resulting power per unit area now reaching the surface?

Randomly polarized light of intensity I0 is passed through two polarizers whose transmission axes differ by 45°. What is the intensity of the light that has passed through both polarizers?

A circularly polarized EM wave has an electric field magnitude 3.0 mV/m. If the wave passes through a polarizer, what will be the amplitude of the electric field in the transmitted wave?

When light passes from one medium into another with a different index of refraction, which of the following does or do NOT change?

A circularly polarized EM wave with intensity I0 is incident on a polarizer. What is the intensity of the transmitted wave?

In vacuum, the components of an EM wave are Ey = (50 V/m) cos [(5.0 m−1)x + ωt], Ex = 0, and Ez = 0. What is the amplitude of the magnetic field for this wave?

Light from an astronomical source is found to be shifted to a frequency one percent lower than had the source been at rest. What relative velocity could cause such a shift?

Electromagnetic waves of wavelength 1000 nm are classified as

A dipole radio transmitter has its rod-shaped antenna oriented vertically. At a point due south of the transmitter, the radio waves have their magnetic field

In vacuum, the components of an EM wave are Ey = (50 V/m) cos [(5.00 m−1)x + ωt], Ex = 0, and Ez = 0. In what direction is this wave moving?

If unpolarized light with Erms = 20 V/m is passed through a polarizer, what is the transmitted Erms?

Light passes from medium one (v1) to medium two (v2). If v1 < v2 then at the boundary

If you are facing north with the Sun directly overhead, the light coming to your eyes from the sky just above the horizon is

An electromagnetic wave is created by

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Radiation of intensity 1.00 kW/m² is incident on an area perpendicular to the incoming light. The area is now rotated 20° about an axis perpendicular to the incoming light. What is the resulting power per unit area now reaching the surface?

Randomly polarized light of intensity I₀ is passed through two polarizers whose transmission axes differ by 45°. What is the intensity of the light that has passed through both polarizers?

A circularly polarized EM wave with intensity I₀ is incident on a polarizer. What is the intensity of the transmitted wave?

In vacuum, the components of an EM wave are E_y = (50 V/m) cos [(5.0 m⁻¹)x + ωt], E_x = 0, and E_z = 0. What is the amplitude of the magnetic field for this wave?

In vacuum, the components of an EM wave are E_y = (50 V/m) cos [(5.00 m⁻¹)x + ωt], E_x = 0, and E_z = 0. In what direction is this wave moving?

If unpolarized light with E_rms = 20 V/m is passed through a polarizer, what is the transmitted E_rms?

Light passes from medium one (v₁) to medium two (v₂). If v₁ < v₂ then at the boundary