Question 1

One hundred turns of insulated copper wire are wrapped around an iron core of cross-sectional area 0.100 m2. The circuit is completed by connecting the coil to a 10- Ω\OmegaΩ  resistor. As the magnetic field along the coil axis changes from 1.00 T in one direction to 1.00 T in the other direction, the total charge that flows through the resistor is:

Accepted Answer

A)   0.01 C
B)   0.02 C
C)   0.2 C
D)   1 C
E)   2 C F) B) and E)
G) A) and E)

Question 2

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. When the total emf of the combination is 16 V, the rate of change of the current in the larger inductor is:

Accepted Answer

A)   2.0 * 103 A/s
B)   3.6 * 103 A/s
C)   4.6 * 103 A/s
D)   7.0 *103 A/s
E)   8.1 * 103 A/sF) A) and E)
G) A) and B)

Question 3

A circular loop of wire rotates about a diameter in a magnetic field that is perpendicular to the axis of rotation. Looking in the direction of the field at the loop the induced current is:

Accepted Answer

A)   always clockwise
B)   always counterclockwise
C)   clockwise in the lower half of the loop and counterclockwise in the upper half
D)   clockwise in the upper half of the loop and counterclockwise in the lower half
E)   sometimes clockwise and sometimes counterclockwiseF) A) and E)
G) C) and E)

Question 4

A vertical bar magnet is dropped through the center of a horizontal loop of wire, with its north pole leading. At the instant when the midpoint of the magnet is in the plane of the loop, the induced current in the loop, viewed from above, is:

Accepted Answer

A)   maximum and clockwise
B)   maximum and counterclockwise
C)   not maximum but clockwise
D)   not maximum but counterclockwise
E)   essentially zeroF) A) and D)
G) All of the above

Question 5

Which statement about eddy currents is false?

Accepted Answer

A)   They can be prevented by cutting a slot in a solid conducting plate, to prevent electrons from being able to make a complete circuit.
B)   The mechanical energy that is lost when eddy currents are created returns when the eddy currents cease.
C)   They can be used as a passive braking system, as no external power source is needed if permanent magnets are used.
D)   They are created in solid conducting plates as they move in and out of magnetic fields.
E)   The faster the conductor moves, the larger the eddy currents will be.F) A) and D)
G) All of the above

Question 6

As a loop of wire with a resistance of 10   Ω\OmegaΩ moves in a non-uniform magnetic field, it loses kinetic energy at a uniform rate of 5 mJ/s. The induced emf in the loop is:

Accepted Answer

A)   0 V
B)   0.22 V
C)   0.28 V
D)   2.0 V
E)   cannot be calculated from the given data F) B) and E)
G) D) and E)

Question 7

The emf developed in a coil X due to the current in a neighboring coil Y is proportional to the:

Accepted Answer

A)   magnetic field in X
B)   rate of change of magnetic field in X
C)   resistance of X
D)   thickness of the wire in X
E)   current in YF) C) and D)
G) D) and E)

Question 8

A 6.0 mH inductor is in a circuit. At the instant the current is 5.0 A and its rate of change is 200 A/s, the rate with which the energy stored in the inductor is increasing is:

Accepted Answer

A)   7.5*10-2 W
B)   3.0 W
C)   6.0 W
D)   120 W
E)   240 WF) C) and D)
G) A) and B)

Question 9

1 weber is the same as:

Accepted Answer

A)   1 V.s
B)   1 T.s
C)   1 T/m
D)   1 V/s
E)   1 T/m2F) A) and C)
G) A) and E)

Question 10

A 10 turn conducting loop with a radius of 3.0 cm spins at 60 revolutions per second in a magnetic field of 0.50 T. The maximum emf generated is:

Accepted Answer

A)   0.014 V
B)   0.085 V
C)   0.53 V
D)   0.85 V
E)   5.3 VF) A) and D)
G) A) and C)

Question 11

The figure shows a bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, a constant magnetic field between the rails should be in what direction?

Accepted Answer

A)   Right
B)   Left
C)   Into the page
D)   Out of the page
E)   Impossible, cannot be done with a constant magnetic fieldF) A) and E)
G) A) and D)

Question 12

An inductance L, resistance R, and ideal battery of emf are wired in series and the circuit is allowed to come to equilibrium. A switch in the circuit is opened at time t = 0, at which time the current is /R. At any later time t the potential difference across the resistor is given by:

Accepted Answer

A)   (1 - e-Lt/R) 
B)   e-Lt/R
C)   (1 + e-Rt/L) 
D)   e-Rt/L
E)   (1 - e-Rt/L) F) C) and E)
G) A) and D)

Question 13

The diagram shows an inductor that is part of a circuit. The direction of the emf induced in the inductor is indicated. Which of the following is possible?

Accepted Answer

A)   The current is constant and rightward
B)   The current is constant and leftward
C)   The current is increasing and rightward
D)   The current is increasing and leftward
E)   None of the aboveF) C) and E)
G) A) and D)

Question 14

A changing magnetic field pierces the interior of a circuit containing three identical resistors. Two voltmeters are connected as shown. V1 reads 1 mV across R. V2 reads the voltage across the other two resistors, which is: 1 reads 1 mV across R. V2 reads the voltage across the other two resistors, which is:   A)  0 V B)  1/3 mV C)  1/2 mV D)  1 mV E)  2 mV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   0 V
B)   1/3 mV
C)   1/2 mV
D)   1 mV
E)   2 mVF) A) and D)
G) A) and E)

Question 15

The unit "henry" is equivalent to:

Accepted Answer

A)   volt.second/ampere
B)   volt/second
C)   ohm
D)   ampere.volt/second
E)   ampere.second/voltF) D) and E)
G) B) and E)

Question 16

A rod with resistance R lies across frictionless conducting rails in a constant uniform magnetic field B, as shown. Assume the rails have negligible resistance. The magnitude of the force that must be applied by a person to pull the rod to the right at constant speed v is: 2L2v/R E)  B2Lxv/R" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   0
B)   BLv
C)   BLv/R
D)   B2L2v/R
E)   B2Lxv/RF) C) and E)
G) None of the above

Question 17

Faraday's law states that an induced emf is proportional to:

Accepted Answer

A)   the rate of change of the magnetic field
B)   the rate of change of the electric field
C)   the rate of change of the magnetic flux
D)   the rate of change of the electric flux
E)   zeroF) All of the above
G) B) and C)

Question 18

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. The equivalent inductance is:

Accepted Answer

A)   0.13 mH
B)   0.51 mH
C)   1.0 mH
D)   2.0 mH
E)   8.0 mHF) None of the above
G) B) and E)

Question 19

A single loop of wire with a radius of 7.5 cm rotates about a diameter in a uniform magnetic field of 1.6 T. To produce a maximum emf of 1.0 V, it should rotate at:

Accepted Answer

A)   0 rad/s
B)   2.7 rad/s
C)   5.6 rad/s
D)   35 rad/s
E)   71 rad/sF) A) and D)
G) A) and E)

Question 20

If both the resistance and the inductance in an LR series circuit are doubled the new inductive time constant will be:

Accepted Answer

A)   twice the old
B)   four times the old
C)   half the old
D)   one-fourth the old
E)   unchangedF) D) and E)
G) B) and C)

Exam 30: Induction and Inductance

A 6.0 mH inductor is in a circuit. At the instant the current is 5.0 A and its rate of change is 200 A/s, the rate with which the energy stored in the inductor is increasing is:

Correct Answer
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A single loop of wire with a radius of 7.5 cm rotates about a diameter in a uniform magnetic field of 1.6 T. To produce a maximum emf of 1.0 V, it should rotate at:

Correct Answer
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As a loop of wire with a resistance of 10 $\Omega$ moves in a non-uniform magnetic field, it loses kinetic energy at a uniform rate of 5 mJ/s. The induced emf in the loop is:

Correct Answer
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A 10 turn conducting loop with a radius of 3.0 cm spins at 60 revolutions per second in a magnetic field of 0.50 T. The maximum emf generated is:

Correct Answer
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The diagram shows an inductor that is part of a circuit. The direction of the emf induced in the inductor is indicated. Which of the following is possible?

Correct Answer
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A changing magnetic field pierces the interior of a circuit containing three identical resistors. Two voltmeters are connected as shown. V₁ reads 1 mV across R. V₂ reads the voltage across the other two resistors, which is:

Correct Answer
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A circular loop of wire rotates about a diameter in a magnetic field that is perpendicular to the axis of rotation. Looking in the direction of the field at the loop the induced current is:

Correct Answer
verified

If both the resistance and the inductance in an LR series circuit are doubled the new inductive time constant will be:

Correct Answer
verified

The emf developed in a coil X due to the current in a neighboring coil Y is proportional to the:

Correct Answer
verified

1 weber is the same as:

Correct Answer
verified

A rod with resistance R lies across frictionless conducting rails in a constant uniform magnetic field B, as shown. Assume the rails have negligible resistance. The magnitude of the force that must be applied by a person to pull the rod to the right at constant speed v is:

Correct Answer
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Correct Answer
verified

A vertical bar magnet is dropped through the center of a horizontal loop of wire, with its north pole leading. At the instant when the midpoint of the magnet is in the plane of the loop, the induced current in the loop, viewed from above, is:

Correct Answer
verified

The figure shows a bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, a constant magnetic field between the rails should be in what direction?

Correct Answer
verified

Which statement about eddy currents is false?

Correct Answer
verified

An inductance L, resistance R, and ideal battery of emf are wired in series and the circuit is allowed to come to equilibrium. A switch in the circuit is opened at time t = 0, at which time the current is /R. At any later time t the potential difference across the resistor is given by:

Correct Answer
verified

Faraday's law states that an induced emf is proportional to:

Correct Answer
verified

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. The equivalent inductance is:

Correct Answer
verified

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. When the total emf of the combination is 16 V, the rate of change of the current in the larger inductor is:

Correct Answer
verified

The unit "henry" is equivalent to:

Correct Answer
verified

Exam 30: Induction and Inductance

A 6.0 mH inductor is in a circuit. At the instant the current is 5.0 A and its rate of change is 200 A/s, the rate with which the energy stored in the inductor is increasing is:

Correct AnswerverifiedShow Answer

A single loop of wire with a radius of 7.5 cm rotates about a diameter in a uniform magnetic field of 1.6 T. To produce a maximum emf of 1.0 V, it should rotate at:

Correct AnswerverifiedShow Answer

As a loop of wire with a resistance of 10 Ω\OmegaΩ moves in a non-uniform magnetic field, it loses kinetic energy at a uniform rate of 5 mJ/s. The induced emf in the loop is:

Correct AnswerverifiedShow Answer

A 10 turn conducting loop with a radius of 3.0 cm spins at 60 revolutions per second in a magnetic field of 0.50 T. The maximum emf generated is:

Correct AnswerverifiedShow Answer

The diagram shows an inductor that is part of a circuit. The direction of the emf induced in the inductor is indicated. Which of the following is possible?

Correct AnswerverifiedShow Answer

A changing magnetic field pierces the interior of a circuit containing three identical resistors. Two voltmeters are connected as shown. V1 reads 1 mV across R. V2 reads the voltage across the other two resistors, which is:

Correct AnswerverifiedShow Answer

A circular loop of wire rotates about a diameter in a magnetic field that is perpendicular to the axis of rotation. Looking in the direction of the field at the loop the induced current is:

Correct AnswerverifiedShow Answer

If both the resistance and the inductance in an LR series circuit are doubled the new inductive time constant will be:

Correct AnswerverifiedShow Answer

The emf developed in a coil X due to the current in a neighboring coil Y is proportional to the:

Correct AnswerverifiedShow Answer

1 weber is the same as:

Correct AnswerverifiedShow Answer

A rod with resistance R lies across frictionless conducting rails in a constant uniform magnetic field B, as shown. Assume the rails have negligible resistance. The magnitude of the force that must be applied by a person to pull the rod to the right at constant speed v is:

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A vertical bar magnet is dropped through the center of a horizontal loop of wire, with its north pole leading. At the instant when the midpoint of the magnet is in the plane of the loop, the induced current in the loop, viewed from above, is:

Correct AnswerverifiedShow Answer

The figure shows a bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, a constant magnetic field between the rails should be in what direction?

Correct AnswerverifiedShow Answer

Which statement about eddy currents is false?

Correct AnswerverifiedShow Answer

An inductance L, resistance R, and ideal battery of emf are wired in series and the circuit is allowed to come to equilibrium. A switch in the circuit is opened at time t = 0, at which time the current is /R. At any later time t the potential difference across the resistor is given by:

Correct AnswerverifiedShow Answer

Faraday's law states that an induced emf is proportional to:

Correct AnswerverifiedShow Answer

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. The equivalent inductance is:

Correct AnswerverifiedShow Answer

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. When the total emf of the combination is 16 V, the rate of change of the current in the larger inductor is:

Correct AnswerverifiedShow Answer

The unit "henry" is equivalent to:

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

As a loop of wire with a resistance of 10 $\Omega$ moves in a non-uniform magnetic field, it loses kinetic energy at a uniform rate of 5 mJ/s. The induced emf in the loop is:

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

A changing magnetic field pierces the interior of a circuit containing three identical resistors. Two voltmeters are connected as shown. V₁ reads 1 mV across R. V₂ reads the voltage across the other two resistors, which is:

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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