Question 1

What would the speed of an observer be if a red (4.688 × 1014 Hz) traffic light appeared green (5.555 × 1014 Hz) to the observer?

Accepted Answer

A) 4.445 × 108 m/s 
B) 2.219 × 108 m/s 
C) 8.438 × 107 m/s 
D) 5.548 × 107 m/s 
E) 2.890 × 106 m/s 
A) 4.445 × 108 m/s 
B) 2.219 × 108 m/s 
C) 8.438 × 107 m/s 
D) 5.548 × 107 m/s 
E) 2.890 × 106 m/s

Question 2

A cellular telephone transmits electromagnetic waves at a frequency of 835 MHz. What is the wavelength of these waves?

Accepted Answer

A) 0.0146 m 
B) 0.359 m 
C) 0.842 m 
D) 1.62 m 
E) 2.47 m 
A) 0.0146 m 
B) 0.359 m 
C) 0.842 m 
D) 1.62 m 
E) 2.47 m

Question 3

Which one of the following statements concerning the wavelength of an electromagnetic wave in a vacuum is true?

Accepted Answer

A) The wavelength is independent of the speed of the wave for a fixed frequency. 
B) The wavelength is inversely proportional to the speed of the wave. 
C) The wavelength is the same for all types of electromagnetic waves. 
D) The wavelength is directly proportional to the frequency of the wave. 
E) The wavelength is inversely proportional to the frequency of the wave. 
A) The wavelength is independent of the speed of the wave for a fixed frequency. 
B) The wavelength is inversely proportional to the speed of the wave. 
C) The wavelength is the same for all types of electromagnetic waves. 
D) The wavelength is directly proportional to the frequency of the wave. 
E) The wavelength is inversely proportional to the frequency of the wave.

Question 4

The peak value of the electric field component of an electromagnetic wave is E. At a particular instant, the intensity of the wave is of 0.020 W/m2. If the electric field were increased to 5E, what would be the intensity of the wave?

Accepted Answer

A) 0.020 W/m2 
B) 0.10 W/m2 
C) 0.25 W/m2 
D) 0.50 W/m2 
E) 1.0 W/m2 
A) 0.020 W/m2 
B) 0.10 W/m2 
C) 0.25 W/m2 
D) 0.50 W/m2 
E) 1.0 W/m2

Question 5

A linearly polarized electromagnetic wave is sent through two sheets of polarizing material. The first sheet, A, is oriented so that its transmission axis makes an angle of 30° with respect to the incident electric field of the wave. The second sheet, B, is oriented so that its transmission axis makes an angle of 90° with the incident electric field of the wave. The incident beam has an electric field of peak magnitude ES1U1B10S1U1B0 and average intensity SS1U1B10S1U1B0.  
-What is the peak value of the electric field amplitude after it goes through sheet A?

Accepted Answer

A) 0.30E0 
B) 0.50E0 
C) 0.60E0 
D) 0.75E0 
E) 0.87E0 
A) 0.30E0 
B) 0.50E0 
C) 0.60E0 
D) 0.75E0 
E) 0.87E0

Question 6

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna.  
-What is the average total energy density of this electromagnetic wave?

Accepted Answer

A) 6.2 × 10-11 J/m3 
B) 8.6 × 10-11 J/m3 
C) 1.1 × 10-10 J/m3 
D) 1.8 × 10-10 J/m3 
E) 4.4 × 10-10 J/m3 
A) 6.2 × 10-11 J/m3 
B) 8.6 × 10-11 J/m3 
C) 1.1 × 10-10 J/m3 
D) 1.8 × 10-10 J/m3 
E) 4.4 × 10-10 J/m3

Question 7

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna.  
-Determine the wavelength of the wave.

Accepted Answer

A) 0.30 m 
B) 0.60 m 
C) 0.79 m 
D) 1.2 m 
E) 2.3 m 
A) 0.30 m 
B) 0.60 m 
C) 0.79 m 
D) 1.2 m 
E) 2.3 m

Question 8

Which one of the following statements concerning electromagnetic waves is false?

Accepted Answer

A) Electromagnetic waves carry energy. 
B) X-rays have longer wavelengths than radio waves. 
C) In vacuum, all electromagnetic waves travel at the same speed. 
D) Lower frequency electromagnetic waves can be produced by oscillating circuits. 
E) They consist of mutually perpendicular electric and magnetic fields that oscillate perpendicular to the direction of propagation. 
A) Electromagnetic waves carry energy. 
B) X-rays have longer wavelengths than radio waves. 
C) In vacuum, all electromagnetic waves travel at the same speed. 
D) Lower frequency electromagnetic waves can be produced by oscillating circuits. 
E) They consist of mutually perpendicular electric and magnetic fields that oscillate perpendicular to the direction of propagation.

Question 9

A linearly polarized electromagnetic wave is sent through two sheets of polarizing material. The first sheet, A, is oriented so that its transmission axis makes an angle of 30° with respect to the incident electric field of the wave. The second sheet, B, is oriented so that its transmission axis makes an angle of 90° with the incident electric field of the wave. The incident beam has an electric field of peak magnitude ES1U1B10S1U1B0 and average intensity SS1U1B10S1U1B0.  
-What is the average intensity of the wave after it passes through B?

Accepted Answer

A) 0.19S0 
B) 0.34S0 
C) 0.43S0 
D) 0.50S0 
E) zero 
A) 0.19S0 
B) 0.34S0 
C) 0.43S0 
D) 0.50S0 
E) zero

Question 10

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna.  
-What is the magnitude of the magnetic field at t = 6.0 × 10-9 s?

Accepted Answer

A) 1.7 × 10-8 T 
B) 2.3 × 10-8 T 
C) 2.8 × 10-8 T 
D) 3.3 × 10-8 T 
E) zero tesla 
A) 1.7 × 10-8 T 
B) 2.3 × 10-8 T 
C) 2.8 × 10-8 T 
D) 3.3 × 10-8 T 
E) zero tesla

Question 11

The electromagnetic wave of the radiation field from a wire antenna travels toward the plane of your paper (which is in the -z direction). At time t = 0 s, the wave strikes your paper at normal incidence. The magnetic field vector at point O in the figure points in the -y direction and has a magnitude of 4.0 × 10S1U1P1-S1S1P0S1U1P18S1S1P0 T. The frequency of the wave is 1.0 × 10S1U1P116S1S1P0 Hz.  
-What is the rms value of the electric field? Assume that the figure shows the peak value of   .

Accepted Answer

A) 7.5 N/C 
B) 8.5 N/C 
C) 17 N/C 
D) 1.1 × 104 N/C 
E) 8.5 × 10-3 N/C 
A) 7.5 N/C 
B) 8.5 N/C 
C) 17 N/C 
D) 1.1 × 104 N/C 
E) 8.5 × 10-3 N/C

Question 12

The amplitude of the electric field component of an electromagnetic wave is increased from E to 3E. What is the corresponding change in the intensity of the wave?

Accepted Answer

A) The intensity is unchanged by the increase in E. 
B) The intensity increases by a factor of nine. 
C) The intensity increases by a factor of three. 
D) The intensity decreases by a factor of three. 
E) The intensity decreases by a factor of nine. 
A) The intensity is unchanged by the increase in E. 
B) The intensity increases by a factor of nine. 
C) The intensity increases by a factor of three. 
D) The intensity decreases by a factor of three. 
E) The intensity decreases by a factor of nine.

Question 13

The magnitude of the magnetic field component of a plane polarized electromagnetic wave traveling in vacuum is given by By = Bo sin[k z - $\omega$t]. Which one of the following statements concerning this electromagnetic wave is true?

Accepted Answer

A) The wavelength is equal to k/$\omega$. 
B) The wave propagates in the y direction. 
C) The wave is polarized in the x direction. 
D) The electric field component vibrates in the z direction. 
E) The electric field component has a magnitude of E = cBo cos[k z - $\omega$t]. 
A) The wavelength is equal to k/$\omega$. 
B) The wave propagates in the y direction. 
C) The wave is polarized in the x direction. 
D) The electric field component vibrates in the z direction. 
E) The electric field component has a magnitude of E = cBo cos[k z - $\omega$t].

Question 14

Which one of the following statements concerning the energy carried by an electromagnetic wave is true?

Accepted Answer

A) The energy is carried only by the electric field. 
B) More energy is carried by the electric field than by the magnetic field. 
C) The energy is carried equally by the electric and magnetic fields. 
D) More energy is carried by the magnetic field than by the electric field. 
E) The energy is carried only by the magnetic field. 
A) The energy is carried only by the electric field. 
B) More energy is carried by the electric field than by the magnetic field. 
C) The energy is carried equally by the electric and magnetic fields. 
D) More energy is carried by the magnetic field than by the electric field. 
E) The energy is carried only by the magnetic field.

Question 15

The electromagnetic wave of the radiation field from a wire antenna travels toward the plane of your paper (which is in the -z direction). At time t = 0 s, the wave strikes your paper at normal incidence. The magnetic field vector at point O in the figure points in the -y direction and has a magnitude of 4.0 × 10S1U1P1-S1S1P0S1U1P18S1S1P0 T. The frequency of the wave is 1.0 × 10S1U1P116S1S1P0 Hz.  
-What is the magnitude of the associated electric field at time t = 0 s?

Accepted Answer

A) 7.5 × 10-3 N/C 
B) 1.3 N/C 
C) 7.5 N/C 
D) 12 N/C 
E) 7.5 × 104 N/C 
A) 7.5 × 10-3 N/C 
B) 1.3 N/C 
C) 7.5 N/C 
D) 12 N/C 
E) 7.5 × 104 N/C

Question 16

Light emerges from a polarizer that has its transmission axis located along the x axis. The light then passes through two additional sheets of polarizing material. It is desired to orient the two sheets so that, after passing through both of them, the electromagnetic wave has the maximum possible intensity and is polarized 90° with respect to the x axis. How should the transmission axes of the sheets be oriented? Note: the following answers give the angles that the transmission axes make with respect to the x axis.

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 17

What is the correct order, beginning with shortest wavelength and extending to the longest wavelength, of the following colors in the visible light spectrum: blue, green, red, violet, and yellow?

Accepted Answer

A) red, yellow, blue, green, violet 
B) violet, blue, yellow, red, green 
C) red, yellow, green, blue, violet 
D) violet, blue, green, yellow, red 
E) red, blue, violet, green, yellow 
A) red, yellow, blue, green, violet 
B) violet, blue, yellow, red, green 
C) red, yellow, green, blue, violet 
D) violet, blue, green, yellow, red 
E) red, blue, violet, green, yellow

Question 18

An electromagnetic wave has an electric field with a peak value of 250 N/C. What is the average intensity of the wave?

Accepted Answer

A) 0.66 W/m2 
B) 0.89 W/m2 
C) 83 W/m2 
D) 120 W/m2 
E) 170 W/m2 
A) 0.66 W/m2 
B) 0.89 W/m2 
C) 83 W/m2 
D) 120 W/m2 
E) 170 W/m2

Question 19

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna.  
-What is the magnitude of the magnetic field at t = 6.67 × 10-10 s?

Accepted Answer

A) 1.7 × 10-8 T 
B) 2.3 × 10-8 T 
C) 2.9 × 10-8 T 
D) 3.3 × 10-8 T 
E) zero tesla 
A) 1.7 × 10-8 T 
B) 2.3 × 10-8 T 
C) 2.9 × 10-8 T 
D) 3.3 × 10-8 T 
E) zero tesla

Question 20

The electromagnetic wave of the radiation field from a wire antenna travels toward the plane of your paper (which is in the -z direction). At time t = 0 s, the wave strikes your paper at normal incidence. The magnetic field vector at point O in the figure points in the -y direction and has a magnitude of 4.0 × 10S1U1P1-S1S1P0S1U1P18S1S1P0 T. The frequency of the wave is 1.0 × 10S1U1P116S1S1P0 Hz.  
-What is the intensity of the electromagnetic wave at time t = 0 s?

Accepted Answer

A) 0.24 W/m2 
B) 0.38 W/m2 
C) 0.48 W/m2 
D) 0.76 W/m2 
E) 24 W/m2 
A) 0.24 W/m2 
B) 0.38 W/m2 
C) 0.48 W/m2 
D) 0.76 W/m2 
E) 24 W/m2

Exam 24: Electromagnetic Waves

What would the speed of an observer be if a red (4.688 × 1014 Hz) traffic light appeared green (5.555 × 1014 Hz) to the observer?

A cellular telephone transmits electromagnetic waves at a frequency of 835 MHz. What is the wavelength of these waves?

Which one of the following statements concerning the wavelength of an electromagnetic wave in a vacuum is true?

The peak value of the electric field component of an electromagnetic wave is E. At a particular instant, the intensity of the wave is of 0.020 W/m2. If the electric field were increased to 5E, what would be the intensity of the wave?

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna. -What is the average total energy density of this electromagnetic wave?

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna. -Determine the wavelength of the wave.

Which one of the following statements concerning electromagnetic waves is false?

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna. -What is the magnitude of the magnetic field at t = 6.0 × 10-9 s?

The amplitude of the electric field component of an electromagnetic wave is increased from E to 3E. What is the corresponding change in the intensity of the wave?

The magnitude of the magnetic field component of a plane polarized electromagnetic wave traveling in vacuum is given by By = Bo sin[k z - ω\omegaω t]. Which one of the following statements concerning this electromagnetic wave is true?

Which one of the following statements concerning the energy carried by an electromagnetic wave is true?

What is the correct order, beginning with shortest wavelength and extending to the longest wavelength, of the following colors in the visible light spectrum: blue, green, red, violet, and yellow?

An electromagnetic wave has an electric field with a peak value of 250 N/C. What is the average intensity of the wave?

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna. -What is the magnitude of the magnetic field at t = 6.67 × 10-10 s?

Introduction and Mathematical Concepts

Kinematics in One Dimension

Kinematics in Two Dimensions

Forces and Newtons Laws of Motion

Dynamics of Uniform Circular Motion

Work and Energy

Impulse and Momentum

Rotational Kinematics

Rotational Dynamics

Simple Harmonic Motion and Elasticity

Fluids

Temperature and Heat

The Transfer of Heat

The Ideal Gas Law and Kinetic Theory

Thermodynamics

Waves and Sound

The Principle of Linear Superposition and Interference Phenomena

Electric Forces and Electric Fields

Electric Potential Energy and the Electric Potential

Electric Circuits

Magnetic Forces and Magnetic Fields

Electromagnetic Induction

Alternating Current Circuits

The Refl Ection of Light: Mirrors

The Refraction of Light: Lenses and Optical Instruments

Interference and the Wave Nature of Light

Special Relativity

Particles and Waves

The Nature of the Atom

Nuclear Physics and Radioactivity

Ionizing Radiation, Nuclear Energy, and Elementary Particles

Filters

What would the speed of an observer be if a red (4.688 × 10¹⁴ Hz) traffic light appeared green (5.555 × 10¹⁴ Hz) to the observer?

The peak value of the electric field component of an electromagnetic wave is E. At a particular instant, the intensity of the wave is of 0.020 W/m². If the electric field were increased to 5E, what would be the intensity of the wave?

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna. -What is the magnitude of the magnetic field at t = 6.0 × 10^-⁹ s?

The magnitude of the magnetic field component of a plane polarized electromagnetic wave traveling in vacuum is given by B_y = B_o sin[k z - $\omega$ t]. Which one of the following statements concerning this electromagnetic wave is true?

The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna. -What is the magnitude of the magnetic field at t = 6.67 × 10^-¹⁰ s?