Question 1

A coil with a self-inductance of 0.75 mH experiences a constant current buildup from zero to 10 A in 0.25 s.What is the induced emf during this interval?

Accepted Answer

A)  0.045 V
B)  0.030 V
C)  0.47 V
D)  0.019 VE) C) and D)
F) B) and D) B

Question 2

An air-core inductor has 1 000 turns/m and an internal volume of 3.0 cm3.What is its inductance?

Accepted Answer

A)  3.8 mH
B)  38 mH
C)  0.38 H
D)  Insufficient information is given.E) A) and B)
F) All of the above A

Question 3

An RL series circuit has the following components: 5.0-mH coil,1.0-W resistor,12-V battery,ammeter and switch.What is the time constant of this circuit?

Accepted Answer

A)  12 x 10-3 s
B)  5.0 x 10-3 s
C)  2.5 x 10-2 s
D)  200 sE) None of the above
F) C) and D)

Question 4

Superconductors have been discussed as a means for electrical energy storage.Because they are resistanceless,a current once started in a loop would continue without loss.If a current of 1.0 ´ 104 A were started in a huge toroidal coil of radius 1.0 km and inductance 50 H,how much electrical energy (in kWh) could be stored?

Accepted Answer

A)  300 kWh
B)  480 kWh
C)  690 kWh
D)  840 kWhE) A) and B)
F) A) and C)

Question 5

A square coil,enclosing an area with sides 2.0 cm long,is wrapped with 2 500 turns of wire.A uniform magnetic field perpendicular to its plane is turned on and increases to 0.25 T during an interval of 1.0 s.What average voltage is induced in the coil?

Accepted Answer

A)  0.25 V
B)  0.12 V
C)  2.0 V
D)  2.5 VE) C) and D)
F) None of the above

Question 6

The units T·m2/s are equivalent to:

Accepted Answer

A)  W.
B)  V.
C)  N/m.
D)  webers.E) C) and D)
F) All of the above

Question 7

A uniform 4.5-T magnetic field passes through the plane of a wire loop 0.10 m2 in area.What flux passes through the loop when the direction of the 4.5-T field is at a 30  °\degree°  angle to the normal of the loop plane?

Accepted Answer

A)  5.0 T*m2
B)  0.52 T*m2
C)  0.39 T*m2
D)  0.225 T*m2 E) A) and B)
F) B) and C)

Question 8

The operation of a tape player to play music depends on which of the following?

Accepted Answer

A)  the Doppler effect
B)  the photoelectric effect
C)  the force acting on a current-carrying wire in a magnetic field
D)  induced current from the motion of a magnet past a wireE) All of the above
F) B) and C)

Question 9

One time constant after an RL circuit has its switch closed,how does the current I in it compare to the maximum current Imax that occurs for this circuit?

Accepted Answer

A)  I > Imax/2
B)  I = Imax/2
C)  I max/2
D)  Without knowing R and L,this cannot be determined.E) B) and C)
F) None of the above

Question 10

How is the energy stored in a current-carrying inductor related to its self-inductance,L?

Accepted Answer

A)  directly proportional to L2
B)  directly proportional to L1/2
C)  directly proportional to L
D)  inversely proportional to LE) A) and C)
F) A) and B)

Question 11

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.As the south pole leaves the loop of wire,the induced current (as viewed from above) will be:

Accepted Answer

A)  clockwise.
B)  counterclockwise.
C)  zero.
D)  along the length of the magnet.E) A) and B)
F) B) and D)

Question 12

What is the minimum frequency with which a 200-turn,flat coil of cross sectional area 300 cm2 can be rotated in a uniform 30-mT magnetic field if the maximum value of the induced emf is to equal 8.0 V?

Accepted Answer

A)  0.030 Hz
B)  2.9 Hz
C)  7.1 Hz
D)  8.4 HzE) A) and B)
F) A) and C)

Question 13

A 500-turn circular coil with an area of 0.050 0 m2 is mounted on a rotating frame,which turns at a rate of 20.0 rad/s in the presence of a 0.050 0-T uniform magnetic field that is perpendicular to the axis of rotation.What is the instantaneous emf in the coil at the moment that the normal to its plane is at a 90.0  °\degree°  angle to the field?

Accepted Answer

A)  zero
B)  12.5 V
C)  21.6 V
D)  25.0 V E) A) and B)
F) All of the above

Question 14

A series circuit contains a 12-V battery,a 2.0-W resistor,and a 3.0-mH inductor.If the switch to the battery is closed at t = 0,find the time required for the current in the circuit to reach 63% of its final value.

Accepted Answer

A)  1.5 ms
B)  3.0 ms
C)  4.0 ms
D)  5.0 msE) None of the above
F) All of the above

Question 15

A double loop of wire (making 2 turns) is in the x-y plane centered at the origin.A uniform magnetic field is increasing at a constant rate in the positive z-direction.Viewed from the positive z-axis,in which direction is the induced magnetic field in the loop?

Accepted Answer

A)  in the positive z-direction
B)  in the negative z-direction
C)  There is no induced field because of the double loop.
D)  There is no induced field because the rate of change of the magnetic field is constant.E) A) and C)
F) None of the above

Question 16

The function of the electric motor is which one of the following conversion processes?

Accepted Answer

A)  mechanical energy to electrical
B)  electrical energy to mechanical
C)  low voltage to high or vice versa
D)  alternating current to directE) B) and D)
F) A) and B)

Question 17

A bar magnet is held above the center of a conducting ring in the horizontal plane.The magnet is dropped so it falls lengthwise toward the center of the ring.Will the falling magnet be attracted toward the ring or be repelled by the ring due to the magnetic interaction of the magnet and the ring?

Accepted Answer

A)  It will be attracted.
B)  It will be repelled.
C)  It will be attracted only if the north end of the magnet is the leading end as it falls toward the ring.
D)  It will be attracted only if the south end of the magnet is the leading end as it falls toward the ring.E) A) and C)
F) A) and B)

Question 18

A circular loop (area = 0.20 m2) turns in a uniform magnetic field with B = 0.13 T.At an instant when the angle between the magnetic field and the normal to the plane of the loop is p rads and is decreasing at the rate of 0.50 rad/s,what is the magnitude of the emf induced in the loop?

Accepted Answer

A)  zero
B)  13 mV
C)  26 mV
D)  20 mVE) B) and D)
F) B) and C) A

Question 19

A coil is rotated in a magnetic field generating an emf given by emf = NBAw sin q,where q = wt.At which angle q is the emf half of its maximum value?

Accepted Answer

A)  0  °\degree° 
B)  30  °\degree° 
C)  45  °\degree° 
D)  60  °\degree°E) None of the above
F) A) and D)

Question 20

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.The induced current will be greatest in magnitude when the magnet is located so that:

Accepted Answer

A)  the loop is near either the north or the south pole.
B)  the loop is near the north pole only.
C)  the loop is near the middle of the magnet.
D)  with no acceleration,the induced current is zero.E) A) and B)
F) All of the above

Exam 20: Induced Voltages and Inductance

A coil with a self-inductance of 0.75 mH experiences a constant current buildup from zero to 10 A in 0.25 s.What is the induced emf during this interval?

Correct Answer
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B

An air-core inductor has 1 000 turns/m and an internal volume of 3.0 cm³.What is its inductance?

Correct Answer
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A

An RL series circuit has the following components: 5.0-mH coil,1.0-W resistor,12-V battery,ammeter and switch.What is the time constant of this circuit?

Correct Answer
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Correct Answer
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A square coil,enclosing an area with sides 2.0 cm long,is wrapped with 2 500 turns of wire.A uniform magnetic field perpendicular to its plane is turned on and increases to 0.25 T during an interval of 1.0 s.What average voltage is induced in the coil?

Correct Answer
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The units T·m²/s are equivalent to:

Correct Answer
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A uniform 4.5-T magnetic field passes through the plane of a wire loop 0.10 m²in area.What flux passes through the loop when the direction of the 4.5-T field is at a 30 $\degree$ angle to the normal of the loop plane?

Correct Answer
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The operation of a tape player to play music depends on which of the following?

Correct Answer
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One time constant after an RL circuit has its switch closed,how does the current I in it compare to the maximum current I_max that occurs for this circuit?

Correct Answer
verified

How is the energy stored in a current-carrying inductor related to its self-inductance,L?

Correct Answer
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A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.As the south pole leaves the loop of wire,the induced current (as viewed from above) will be:

Correct Answer
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What is the minimum frequency with which a 200-turn,flat coil of cross sectional area 300 cm² can be rotated in a uniform 30-mT magnetic field if the maximum value of the induced emf is to equal 8.0 V?

Correct Answer
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Correct Answer
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A series circuit contains a 12-V battery,a 2.0-W resistor,and a 3.0-mH inductor.If the switch to the battery is closed at t = 0,find the time required for the current in the circuit to reach 63% of its final value.

Correct Answer
verified

A double loop of wire (making 2 turns) is in the x-y plane centered at the origin.A uniform magnetic field is increasing at a constant rate in the positive z-direction.Viewed from the positive z-axis,in which direction is the induced magnetic field in the loop?

Correct Answer
verified

The function of the electric motor is which one of the following conversion processes?

Correct Answer
verified

A bar magnet is held above the center of a conducting ring in the horizontal plane.The magnet is dropped so it falls lengthwise toward the center of the ring.Will the falling magnet be attracted toward the ring or be repelled by the ring due to the magnetic interaction of the magnet and the ring?

Correct Answer
verified

A circular loop (area = 0.20 m²) turns in a uniform magnetic field with B = 0.13 T.At an instant when the angle between the magnetic field and the normal to the plane of the loop is p rads and is decreasing at the rate of 0.50 rad/s,what is the magnitude of the emf induced in the loop?

Correct Answer
verified
A

A coil is rotated in a magnetic field generating an emf given by emf = NBAw sin q,where q = wt.At which angle q is the emf half of its maximum value?

Correct Answer
verified

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.The induced current will be greatest in magnitude when the magnet is located so that:

Correct Answer
verified

Exam 20: Induced Voltages and Inductance

A coil with a self-inductance of 0.75 mH experiences a constant current buildup from zero to 10 A in 0.25 s.What is the induced emf during this interval?

Correct AnswerverifiedB

An air-core inductor has 1 000 turns/m and an internal volume of 3.0 cm3.What is its inductance?

Correct AnswerverifiedA

An RL series circuit has the following components: 5.0-mH coil,1.0-W resistor,12-V battery,ammeter and switch.What is the time constant of this circuit?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A square coil,enclosing an area with sides 2.0 cm long,is wrapped with 2 500 turns of wire.A uniform magnetic field perpendicular to its plane is turned on and increases to 0.25 T during an interval of 1.0 s.What average voltage is induced in the coil?

Correct AnswerverifiedShow Answer

The units T·m2/s are equivalent to:

Correct AnswerverifiedShow Answer

A uniform 4.5-T magnetic field passes through the plane of a wire loop 0.10 m2 in area.What flux passes through the loop when the direction of the 4.5-T field is at a 30 °\degree° angle to the normal of the loop plane?

Correct AnswerverifiedShow Answer

The operation of a tape player to play music depends on which of the following?

Correct AnswerverifiedShow Answer

One time constant after an RL circuit has its switch closed,how does the current I in it compare to the maximum current Imax that occurs for this circuit?

Correct AnswerverifiedShow Answer

How is the energy stored in a current-carrying inductor related to its self-inductance,L?

Correct AnswerverifiedShow Answer

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.As the south pole leaves the loop of wire,the induced current (as viewed from above) will be:

Correct AnswerverifiedShow Answer

What is the minimum frequency with which a 200-turn,flat coil of cross sectional area 300 cm2 can be rotated in a uniform 30-mT magnetic field if the maximum value of the induced emf is to equal 8.0 V?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A series circuit contains a 12-V battery,a 2.0-W resistor,and a 3.0-mH inductor.If the switch to the battery is closed at t = 0,find the time required for the current in the circuit to reach 63% of its final value.

Correct AnswerverifiedShow Answer

A double loop of wire (making 2 turns) is in the x-y plane centered at the origin.A uniform magnetic field is increasing at a constant rate in the positive z-direction.Viewed from the positive z-axis,in which direction is the induced magnetic field in the loop?

Correct AnswerverifiedShow Answer

The function of the electric motor is which one of the following conversion processes?

Correct AnswerverifiedShow Answer

A bar magnet is held above the center of a conducting ring in the horizontal plane.The magnet is dropped so it falls lengthwise toward the center of the ring.Will the falling magnet be attracted toward the ring or be repelled by the ring due to the magnetic interaction of the magnet and the ring?

Correct AnswerverifiedShow Answer

A circular loop (area = 0.20 m2) turns in a uniform magnetic field with B = 0.13 T.At an instant when the angle between the magnetic field and the normal to the plane of the loop is p rads and is decreasing at the rate of 0.50 rad/s,what is the magnitude of the emf induced in the loop?

Correct AnswerverifiedA

A coil is rotated in a magnetic field generating an emf given by emf = NBAw sin q,where q = wt.At which angle q is the emf half of its maximum value?

Correct AnswerverifiedShow Answer

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.The induced current will be greatest in magnitude when the magnet is located so that:

Correct AnswerverifiedShow Answer

Correct Answer
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B

An air-core inductor has 1 000 turns/m and an internal volume of 3.0 cm³.What is its inductance?

Correct Answer
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A

Correct Answer
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Correct Answer
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Correct Answer
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The units T·m²/s are equivalent to:

Correct Answer
verified

A uniform 4.5-T magnetic field passes through the plane of a wire loop 0.10 m²in area.What flux passes through the loop when the direction of the 4.5-T field is at a 30 $\degree$ angle to the normal of the loop plane?

Correct Answer
verified

Correct Answer
verified

One time constant after an RL circuit has its switch closed,how does the current I in it compare to the maximum current I_max that occurs for this circuit?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

What is the minimum frequency with which a 200-turn,flat coil of cross sectional area 300 cm² can be rotated in a uniform 30-mT magnetic field if the maximum value of the induced emf is to equal 8.0 V?

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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A circular loop (area = 0.20 m²) turns in a uniform magnetic field with B = 0.13 T.At an instant when the angle between the magnetic field and the normal to the plane of the loop is p rads and is decreasing at the rate of 0.50 rad/s,what is the magnitude of the emf induced in the loop?

Correct Answer
verified
A

Correct Answer
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Correct Answer
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