Question 1

Suppose that the maximum rate of change of current in a "high power" transmission line is 104 A/s. How large a coil (area)  placed 10. meters from the line would have 120. volts (max)  induced in it?

Accepted Answer

A)   2. × 103 m2
B)   6. × 103 m2
C)   6. × 104 m2
D)   2. × 1053 m2
E)   6. × 105 m2F) C) and E)
G) B) and D)

Question 2

A transformer is a device that

Accepted Answer

A)   increases the power level of a circuit.
B)   operates only on AC.
C)   operates on either DC or AC.
D)   operates only on DC.E) A) and B)
F) A) and C)

Question 3

Consider an outer loop of wire surrounding an inner loop of wire, as shown in Figure 20-2.

Suppose the current in the outer loop is counterclockwise and decreasing. What is the direction of the induced current in the inner loop?

Accepted Answer

The answer of Consider an outer loop of wire surrounding...

Question 4

The coil of a generator rotates through one complete turn in a uniform magnetic field 50. times every second. When this generator is connected to an external load, the current through the load reverses directions

Accepted Answer

A)   100 times every second.
B)   50 times every second.
C)   200 times every second.
D)   25 times every second.
E)   75 times every second.F) A) and B)
G) D) and E)

Question 5

An induced emf is produced in a loop or complete circuit whenever the number of magnetic field lines passing through the plane of the loop or circuit changes.

Accepted Answer

A) True 
 B)False

Question 6

Electromagnetic radiation of wavelength 3.5 meters is which type?

Accepted Answer

A)   FM-radio
B)   visible
C)   ultraviolet
D)   microwaves
E)   AM-radioF) B) and D)
G) D) and E)

Question 7

Faraday's law of induction states that the emf induced in a loop of wire is proportional to

Accepted Answer

A)   current divided by time.
B)   the magnetic flux density times the loop's area.
C)   the time variation of the magnetic flux.
D)   the magnetic flux.E) B) and D)
F) None of the above

Question 8

A loop of wire is rotated about a diameter (which is perpendicular to a given magnetic field.)  In one revolution the induced current in the loop reverses direction how many times?

Accepted Answer

A)   4
B)   1
C)   0
D)   3
E)   2F) A) and C)
G) C) and E)

Question 9

Early AM radios required very long antennae wires. FM antennae are often approximately a meter in size. Can you surmise why sensitive FM aerials are much smaller than those AM wires?

Accepted Answer

A sensitive aerial has a size related to...

Question 10

The flux through a coil changes from 4 × 10-5 Wb to 5 × 10-5 Wb in 0.1 s. What emf is induced in this coil?

Accepted Answer

A)   3 × 10-4 V
B)   5 × 10-4 V
C)   7 × 10-4 V
D)   1 × 10-4 V
E)   4 × 10-4 VF) C) and E)
G) C) and D) D

Question 11

In a vacuum, all electromagnetic waves travel at the same speed.

Accepted Answer

A) True 
 B)False

Question 12

An AC generator has 80. rectangular loops on its armature. Each loop is 12. cm long and 8.0 cm wide. The armature rotates at 1200. rpm about an axis parallel to the long side. If the loop rotates in a uniform magnetic field of 0.30 T, which is perpendicular to the axis of rotation, what will be the maximum output voltage of this generator?

Accepted Answer

A)   220 V
B)   124 V
C)   167 V
D)   120  V
E)   182 VF) A) and B)
G) D) and E)

Question 13

A popular novelty contains 4 vanes balanced on a needle in an evacuated globe (see Figure 20-3) The front side of each vane is a shiny mirror and the back side is blackened.  
 
 Since electromagnetic waves exert a "radiation pressure," which way will the vanes rotate when a bright light shines on them?

Accepted Answer

With a "good" vacuum, the vanes rotate c...

Question 14

A flux of 4 × 10-5 Wb is maintained through a coil for 0.5 s. What emf is induced in this coil by this flux?

Accepted Answer

A)   No emf is induced in this coil.
B)   4 × 10-5 V
C)   6 × 10-5 V
D)   2 × 10-5 V
E)   8 × 10-5 VF) B) and D)
G) B) and E)

Question 15

A very long solenoid has 1.0 × 106 turns per meter and a cross-sectional area of 2.0 × 106 m2. A short, secondary coil with 1.0 × 103 turns is wound over the solenoid's midpoint. What emf is induced in the secondary coil if the current in the solenoid is changing at a rate of 4.0 A/s?

Accepted Answer

A)   1.6 V
B)   1.0 V
C)   4.4 V
D)   2.7 V
E)   0.52 VF) C) and E)
G) B) and D)

Question 16

The output of a generator is 440. V at 20. A. It is to be transmitted on a line with resistance of 0.60 ?. To what voltage must the generator output be stepped up with a transformer if the power loss in transmission is not to exceed 0.01% of the original power?

Accepted Answer

A)   4.4 × 105 V
B)   4.4 kV
C)   44.5 kV
D)   22. kV
E)   72.7 kVF) A) and B)
G) A) and C) C

Question 17

A coil lies flat on a table top in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced current in this coil as the field fades?

Accepted Answer

A)   The current flows clockwise initially, and then it flows counterclockwise before stopping.
B)   There is no induced current in this coil.
C)   The induced current flows counterclockwise.
D)   The induced current flows clockwise.E) A) and D)
F) C) and D)

Question 18

The cross-sectional area of an adjustable single loop is reduced from 1.0 m2 to 0.25 m2 in 0.10 s. What is the average emf that is induced in this coil if it is in a region where B = 2.0 T upward, and the coil's plane is perpendicular to B?

Accepted Answer

A)   0 V
B)   15 V
C)   12 V
D)   21 V
E)   18 VF) A) and E)
G) A) and B) B

Question 19

Electromagnetic radiation of wavelength 2.5 cm is which type?

Accepted Answer

A)   microwaves
B)   AM-radio
C)   FM-radio
D)   ultraviolet
E)   visibleF) C) and E)
G) D) and E)

Question 20

A circular loop of wire is rotated at constant angular speed about an axis whose direction can be varied. In a region where a uniform magnetic field points straight down, what must be the orientation of the loop's axis of rotation if the induced emf is to be a maximum?

Accepted Answer

A)   It must be vertical.
B)   It must make an angle of 90° to the direction North.
C)   It must make an angle of 45° to the direction North.
D)   Any horizontal orientation will do.
E)   It must make an angle of 45° to the vertical.F) A) and E)
G) A) and B)

Exam 20: Electromagnetic Induction and Waves

Suppose that the maximum rate of change of current in a "high power" transmission line is 10⁴ A/s. How large a coil (area) placed 10. meters from the line would have 120. volts (max) induced in it?

Correct Answer
verified

A transformer is a device that

Correct Answer
verified

Consider an outer loop of wire surrounding an inner loop of wire, as shown in Figure 20-2. Suppose the current in the outer loop is counterclockwise and decreasing. What is the direction of the induced current in the inner loop?

Correct Answer
verified

The coil of a generator rotates through one complete turn in a uniform magnetic field 50. times every second. When this generator is connected to an external load, the current through the load reverses directions

Correct Answer
verified

An induced emf is produced in a loop or complete circuit whenever the number of magnetic field lines passing through the plane of the loop or circuit changes.

Correct Answer
verified

Electromagnetic radiation of wavelength 3.5 meters is which type?

Correct Answer
verified

Faraday's law of induction states that the emf induced in a loop of wire is proportional to

Correct Answer
verified

A loop of wire is rotated about a diameter (which is perpendicular to a given magnetic field.) In one revolution the induced current in the loop reverses direction how many times?

Correct Answer
verified

Early AM radios required very long antennae wires. FM antennae are often approximately a meter in size. Can you surmise why sensitive FM aerials are much smaller than those AM wires?

Correct Answer
verified
A sensitive aerial has a size related to...
View Answer

The flux through a coil changes from 4 × 10^-5 Wb to 5 × 10^-5 Wb in 0.1 s. What emf is induced in this coil?

Correct Answer
verified
D

In a vacuum, all electromagnetic waves travel at the same speed.

Correct Answer
verified

Correct Answer
verified

A popular novelty contains 4 vanes balanced on a needle in an evacuated globe (see Figure 20-3) The front side of each vane is a shiny mirror and the back side is blackened. Since electromagnetic waves exert a "radiation pressure," which way will the vanes rotate when a bright light shines on them?

Correct Answer
verified
With a "good" vacuum, the vanes rotate c...
View Answer

A flux of 4 × 10^-5 Wb is maintained through a coil for 0.5 s. What emf is induced in this coil by this flux?

Correct Answer
verified

A very long solenoid has 1.0 × 10⁶ turns per meter and a cross-sectional area of 2.0 × 10⁶m². A short, secondary coil with 1.0 × 10³ turns is wound over the solenoid's midpoint. What emf is induced in the secondary coil if the current in the solenoid is changing at a rate of 4.0 A/s?

Correct Answer
verified

The output of a generator is 440. V at 20. A. It is to be transmitted on a line with resistance of 0.60 ?. To what voltage must the generator output be stepped up with a transformer if the power loss in transmission is not to exceed 0.01% of the original power?

Correct Answer
verified
C

A coil lies flat on a table top in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced current in this coil as the field fades?

Correct Answer
verified

The cross-sectional area of an adjustable single loop is reduced from 1.0 m² to 0.25 m² in 0.10 s. What is the average emf that is induced in this coil if it is in a region where B = 2.0 T upward, and the coil's plane is perpendicular to B?

Correct Answer
verified
B

Electromagnetic radiation of wavelength 2.5 cm is which type?

Correct Answer
verified

A circular loop of wire is rotated at constant angular speed about an axis whose direction can be varied. In a region where a uniform magnetic field points straight down, what must be the orientation of the loop's axis of rotation if the induced emf is to be a maximum?

Correct Answer
verified

Exam 20: Electromagnetic Induction and Waves

Suppose that the maximum rate of change of current in a "high power" transmission line is 104 A/s. How large a coil (area) placed 10. meters from the line would have 120. volts (max) induced in it?

Correct AnswerverifiedShow Answer

A transformer is a device that

Correct AnswerverifiedShow Answer

Consider an outer loop of wire surrounding an inner loop of wire, as shown in Figure 20-2. Suppose the current in the outer loop is counterclockwise and decreasing. What is the direction of the induced current in the inner loop?

Correct AnswerverifiedShow Answer

The coil of a generator rotates through one complete turn in a uniform magnetic field 50. times every second. When this generator is connected to an external load, the current through the load reverses directions

Correct AnswerverifiedShow Answer

An induced emf is produced in a loop or complete circuit whenever the number of magnetic field lines passing through the plane of the loop or circuit changes.

Correct AnswerverifiedShow Answer

Electromagnetic radiation of wavelength 3.5 meters is which type?

Correct AnswerverifiedShow Answer

Faraday's law of induction states that the emf induced in a loop of wire is proportional to

Correct AnswerverifiedShow Answer

A loop of wire is rotated about a diameter (which is perpendicular to a given magnetic field.) In one revolution the induced current in the loop reverses direction how many times?

Correct AnswerverifiedShow Answer

Early AM radios required very long antennae wires. FM antennae are often approximately a meter in size. Can you surmise why sensitive FM aerials are much smaller than those AM wires?

Correct AnswerverifiedA sensitive aerial has a size related to...View AnswerShow Answer

The flux through a coil changes from 4 × 10-5 Wb to 5 × 10-5 Wb in 0.1 s. What emf is induced in this coil?

Correct AnswerverifiedD

In a vacuum, all electromagnetic waves travel at the same speed.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A popular novelty contains 4 vanes balanced on a needle in an evacuated globe (see Figure 20-3) The front side of each vane is a shiny mirror and the back side is blackened. Since electromagnetic waves exert a "radiation pressure," which way will the vanes rotate when a bright light shines on them?

Correct AnswerverifiedWith a "good" vacuum, the vanes rotate c...View AnswerShow Answer

A flux of 4 × 10-5 Wb is maintained through a coil for 0.5 s. What emf is induced in this coil by this flux?

Correct AnswerverifiedShow Answer

A very long solenoid has 1.0 × 106 turns per meter and a cross-sectional area of 2.0 × 106 m2. A short, secondary coil with 1.0 × 103 turns is wound over the solenoid's midpoint. What emf is induced in the secondary coil if the current in the solenoid is changing at a rate of 4.0 A/s?

Correct AnswerverifiedShow Answer

The output of a generator is 440. V at 20. A. It is to be transmitted on a line with resistance of 0.60 ?. To what voltage must the generator output be stepped up with a transformer if the power loss in transmission is not to exceed 0.01% of the original power?

Correct AnswerverifiedC

A coil lies flat on a table top in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced current in this coil as the field fades?

Correct AnswerverifiedShow Answer

The cross-sectional area of an adjustable single loop is reduced from 1.0 m2 to 0.25 m2 in 0.10 s. What is the average emf that is induced in this coil if it is in a region where B = 2.0 T upward, and the coil's plane is perpendicular to B?

Correct AnswerverifiedB

Electromagnetic radiation of wavelength 2.5 cm is which type?

Correct AnswerverifiedShow Answer

A circular loop of wire is rotated at constant angular speed about an axis whose direction can be varied. In a region where a uniform magnetic field points straight down, what must be the orientation of the loop's axis of rotation if the induced emf is to be a maximum?

Correct AnswerverifiedShow Answer

Suppose that the maximum rate of change of current in a "high power" transmission line is 10⁴ A/s. How large a coil (area) placed 10. meters from the line would have 120. volts (max) induced in it?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
A sensitive aerial has a size related to...
View Answer

The flux through a coil changes from 4 × 10^-5 Wb to 5 × 10^-5 Wb in 0.1 s. What emf is induced in this coil?

Correct Answer
verified
D

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
With a "good" vacuum, the vanes rotate c...
View Answer

A flux of 4 × 10^-5 Wb is maintained through a coil for 0.5 s. What emf is induced in this coil by this flux?

Correct Answer
verified

A very long solenoid has 1.0 × 10⁶ turns per meter and a cross-sectional area of 2.0 × 10⁶m². A short, secondary coil with 1.0 × 10³ turns is wound over the solenoid's midpoint. What emf is induced in the secondary coil if the current in the solenoid is changing at a rate of 4.0 A/s?

Correct Answer
verified

Correct Answer
verified
C

Correct Answer
verified

The cross-sectional area of an adjustable single loop is reduced from 1.0 m² to 0.25 m² in 0.10 s. What is the average emf that is induced in this coil if it is in a region where B = 2.0 T upward, and the coil's plane is perpendicular to B?

Correct Answer
verified
B

Correct Answer
verified

Correct Answer
verified