Question 1

An electromagnetic wave with components Ey = Eo sin(kx - ωt) and Bz = Bo sin(kx - ωt) is a wave traveling with a speed of

Accepted Answer

A) ω. 
B) ω/k. 
C) k. 
D) k/ω. 
E) ω/k2. 
A) ω. 
B) ω/k. 
C) k. 
D) k/ω. 
E) ω/k2. B

Question 2

The right hand rule for the direction of propagation of the electromagnetic waves is to

Accepted Answer

A) point the forefinger of your right hand toward E vector, middle finger toward the B vector, and the thumb will represent the propagation. 
B) point the middle finger of your right hand toward the E vector, the forefinger toward the B vector, and the thumb will represent the direction of propagation. 
C) point the fingers of your right hand toward the E vector, curl your fingers towards the B vector, and the thumb will point the direction of propagation. 
D) point the fingers of your left hand toward the E vector, curl your fingers towards the B vector, and the thumb will point the direction of propagation. 
E) None of the other answers is correct. 
A) point the forefinger of your right hand toward E vector, middle finger toward the B vector, and the thumb will represent the propagation. 
B) point the middle finger of your right hand toward the E vector, the forefinger toward the B vector, and the thumb will represent the direction of propagation. 
C) point the fingers of your right hand toward the E vector, curl your fingers towards the B vector, and the thumb will point the direction of propagation. 
D) point the fingers of your left hand toward the E vector, curl your fingers towards the B vector, and the thumb will point the direction of propagation. 
E) None of the other answers is correct. C

Question 3

Write Maxwell's Equations in the integral form for free space.

Accepted Answer

Refer to Table 31-1 in the textbook.

Question 4

The momentum of 1 J of energy in an electromagnetic wave is

Accepted Answer

A) 1.5 × 10-9 kg∙m/s. 
B) 3 × 10-9 kg∙m/s. 
C) 1 kg m/s. 
D) 1 × 10-17 kg∙m/s. 
E) 1000 kg m/s. 
A) 1.5 × 10-9 kg∙m/s. 
B) 3 × 10-9 kg∙m/s. 
C) 1 kg m/s. 
D) 1 × 10-17 kg∙m/s. 
E) 1000 kg m/s.

Question 5

A parallel-plate capacitor, made of two circular plates of radius R = 10 cm, is connected in series with a resistor of resistance R = 100 Ω and a battery of emf E = 10 V. What is the maximum value of the magnetic field induced by the displacement current between the plates, at a distance r = 5 cm from the axis of the plates while the capacitor is being charged?

Accepted Answer

A) 3 × 10-7 T 
B) 5 × 10-7 T 
C) 2 × 10-7 T 
D) 1 × 10-7 T 
E) 4 × 10-7 T 
A) 3 × 10-7 T 
B) 5 × 10-7 T 
C) 2 × 10-7 T 
D) 1 × 10-7 T 
E) 4 × 10-7 T

Question 6

A laser with a power of 1.0 mW has a beam radius of 1.0 mm. What is the peak value of the electric field in that beam?

Accepted Answer

A) 490 V/m 
B) 840 V/m 
C) 65 V/m 
D) 120 V/m 
E) 22 V/m 
A) 490 V/m 
B) 840 V/m 
C) 65 V/m 
D) 120 V/m 
E) 22 V/m

Question 7

Using Maxwell's equations it can be shown that electromagnetic waves have a speed in free space of

Accepted Answer

A) (εOμO)-3/2. 
B) (εOμO)-1/2. 
C) εOμO. 
D) (εOμO)-2. 
E) (εOμO)-1. 
A) (εOμO)-3/2. 
B) (εOμO)-1/2. 
C) εOμO. 
D) (εOμO)-2. 
E) (εOμO)-1.

Question 8

If an electromagnetic wave has its magnetic field oscillating in the vertical direction, the direction of oscillation of the electric field is

Accepted Answer

A) east-west. 
B) horizontal. 
C) vertical. 
D) north-south. 
E) circular. 
A) east-west. 
B) horizontal. 
C) vertical. 
D) north-south. 
E) circular.

Question 9

The force per unit area exerted by an electromagnetic wave is called the

Accepted Answer

A) energy density. 
B) power. 
C) intensity. 
D) radiation pressure. 
E) radiation field. 
A) energy density. 
B) power. 
C) intensity. 
D) radiation pressure. 
E) radiation field.

Question 10

If the visible wavelengths of light range from 400 nm to 750 nm, what is the highest frequency associated with visible light?

Accepted Answer

A) 3.0 × 108 Hz 
B) 7.5 × 1014 Hz 
C) 2.3 × 1020 Hz 
D) 4.0 × 1014 Hz 
E) 5.0 × 108 Hz 
A) 3.0 × 108 Hz 
B) 7.5 × 1014 Hz 
C) 2.3 × 1020 Hz 
D) 4.0 × 1014 Hz 
E) 5.0 × 108 Hz

Question 11

If the magnetic field in an EM wave is in the x-direction and the electric field in the wave is in the y-direction, the wave is traveling in the

Accepted Answer

A) x-y plane. 
B) direction halfway between the x- and y-directions. 
C) z-direction. 
D) x-direction. 
E) negative z-direction. 
A) x-y plane. 
B) direction halfway between the x- and y-directions. 
C) z-direction. 
D) x-direction. 
E) negative z-direction.

Question 12

The ratio of the electric field to the magnetic field in the electromagnetic wave is the speed of the light.

Accepted Answer

A) True 
 B)False

Question 13

An electromagnetic wave is propagating towards the west. At a certain moment the direction of the magnetic field vector associated with this wave points vertically up. What is the direction of the electric field vector?

Accepted Answer

A) Horizontal and pointing south 
B) Vertical and pointing down 
C) Horizontal and pointing north 
D) Vertical and pointing up 
E) Horizontal and pointing east 
A) Horizontal and pointing south 
B) Vertical and pointing down 
C) Horizontal and pointing north 
D) Vertical and pointing up 
E) Horizontal and pointing east

Question 14

An electromagnetic wave is a result of electric and magnetic fields acting together.

Accepted Answer

A) True 
 B)False

Question 15

The electric field of a plane electromagnetic pulse in a vacuum is given by Ex = Eo   . What is the corresponding expression for the magnetic field?

Accepted Answer

A) By =  
  
B) By =  
  
C) By =  
  
D) By =  
  
E) By =  
  
A) By =  
  
B) By =  
  
C) By =  
  
D) By =  
  
E) By =

Question 16

The wavelength of an electromagnetic wave is 600 nm. What is its frequency?

Accepted Answer

A) 200 × 1012 Hz 
B) 300 × 1012 Hz 
C) 400 × 1012 Hz 
D) 500 × 1012 Hz 
E) 600 × 1012 Hz 
A) 200 × 1012 Hz 
B) 300 × 1012 Hz 
C) 400 × 1012 Hz 
D) 500 × 1012 Hz 
E) 600 × 1012 Hz

Question 17

If the electric field and magnetic field of an EM wave are given by E = Eo sin(kx - ωt) and B = Bo sin(kx - ωt), and if the value of Eo is 5.1 x 10-5 V/m, what is the value of Bo?

Accepted Answer

A) 1.7 × 1014 T 
B) 1.7 × 103 T 
C) 1.7 × 10-14 T 
D) 1.7 × 104 T 
E) 1.7 × 10-13 T 
A) 1.7 × 1014 T 
B) 1.7 × 103 T 
C) 1.7 × 10-14 T 
D) 1.7 × 104 T 
E) 1.7 × 10-13 T

Question 18

The magnetic field of a plane progressive electromagnetic wave in a vacuum is given by Bz = Bocos(ky - ωt). What is the corresponding expression for the electric field?

Accepted Answer

A) Ex = cBosin(ky - ωt) 
B) Ex = - cBocos(ky - ωt) 
C) Ez = cBosin(ky - ωt) 
D) Ex = cBocos(ky - ωt) 
E) Ex = - cBosin(ky - ωt) 
A) Ex = cBosin(ky - ωt) 
B) Ex = - cBocos(ky - ωt) 
C) Ez = cBosin(ky - ωt) 
D) Ex = cBocos(ky - ωt) 
E) Ex = - cBosin(ky - ωt)

Question 19

The energy per unit volume in an EM wave is

Accepted Answer

A) equally divided between the electric and magnetic fields. 
B) almost entirely in the electric field. 
C) indeterminate. 
D) almost entirely in the magnetic field. 
E) zero. 
A) equally divided between the electric and magnetic fields. 
B) almost entirely in the electric field. 
C) indeterminate. 
D) almost entirely in the magnetic field. 
E) zero.

Question 20

Electromagnetic waves are longitudinal.

Accepted Answer

A) True 
 B)False

Exam 31: Maxwells Equations and Electromagnetic Waves

An electromagnetic wave with components Ey = Eo sin(kx - ωt) and Bz = Bo sin(kx - ωt) is a wave traveling with a speed of

The right hand rule for the direction of propagation of the electromagnetic waves is to

Write Maxwell's Equations in the integral form for free space.

The momentum of 1 J of energy in an electromagnetic wave is

A laser with a power of 1.0 mW has a beam radius of 1.0 mm. What is the peak value of the electric field in that beam?

Using Maxwell's equations it can be shown that electromagnetic waves have a speed in free space of

If an electromagnetic wave has its magnetic field oscillating in the vertical direction, the direction of oscillation of the electric field is

The force per unit area exerted by an electromagnetic wave is called the

If the visible wavelengths of light range from 400 nm to 750 nm, what is the highest frequency associated with visible light?

If the magnetic field in an EM wave is in the x-direction and the electric field in the wave is in the y-direction, the wave is traveling in the

The ratio of the electric field to the magnetic field in the electromagnetic wave is the speed of the light.

An electromagnetic wave is propagating towards the west. At a certain moment the direction of the magnetic field vector associated with this wave points vertically up. What is the direction of the electric field vector?

An electromagnetic wave is a result of electric and magnetic fields acting together.

The electric field of a plane electromagnetic pulse in a vacuum is given by Ex = Eo . What is the corresponding expression for the magnetic field?

The wavelength of an electromagnetic wave is 600 nm. What is its frequency?

If the electric field and magnetic field of an EM wave are given by E = Eo sin(kx - ωt) and B = Bo sin(kx - ωt), and if the value of Eo is 5.1 x 10-5 V/m, what is the value of Bo?

The magnetic field of a plane progressive electromagnetic wave in a vacuum is given by Bz = Bocos(ky - ωt). What is the corresponding expression for the electric field?

The energy per unit volume in an EM wave is

Electromagnetic waves are longitudinal.

Introduction, Measurement, Estimating

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Filters

An electromagnetic wave with components E_y = E_o sin(kx - ωt) and B_z = B_o sin(kx - ωt) is a wave traveling with a speed of

The electric field of a plane electromagnetic pulse in a vacuum is given by E_x = E_o . What is the corresponding expression for the magnetic field?

If the electric field and magnetic field of an EM wave are given by E = E_o sin(kx - ωt) and B = B_o sin(kx - ωt), and if the value of E_o is 5.1 x 10^-5 V/m, what is the value of B_o?

The magnetic field of a plane progressive electromagnetic wave in a vacuum is given by B_z = B_ocos(ky - ωt). What is the corresponding expression for the electric field?