Deck 14: Induction and Inductance

Question 1

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

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) zero

Answer 1

the rate of change of the magnetic flux

Question 2

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

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 Y

Answer 2

rate of change of magnetic field in X

Question 3

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:

A) 0.014 V
B) 0.53 V
C) 5.3 V
D) 18 V
E) 180 V

Answer 3

5.3 V

Question 4

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:

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

Question 5

An electric field is associated with every:

A) magnetic field
B) time-dependent magnetic field
C) time-dependent magnetic flux
D) object moving in a magnetic field
E) conductor moving in a magnetic field

Question 6

A 10-turn ideal solenoid has an inductance of 4.0 mH. To generate an emf of 2.0 V the current should change at a rate of:

A) zero
B) 5.0 A/s
C) 50 A/s
D) 250 A/s
E) 500 A/s

Question 7

A long narrow solenoid has length and a total of N turns, each of which has cross-sectional area A. Its inductance is:

A)
B)
C)
D)
E) none of these

Question 8

A flat coil of wire, having 5 turns, has an inductance L. The inductance of a similar coil having 20 turns is:

A) 4L
B) L/4
C) 16L
D) L/16
E) L

Question 9

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

A) twice the old
B) four times the old
C) half the old
D) one-fourth the old
E) unchanged

Question 10

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

A) 2.0 mH
B) 0.51 mH
C) 0.13 mH
D) 1.0 mH
E) 8.0 mH

Question 11

A 3.5 mH inductor and a 4.5 mH inductor are connected in series and a time varying current is established in them. When the total emf of the combination is 16 V, the emf of the larger inductor is:

A) 7.0 V
B) 9.0 V
C) 2.3 V
D) 28 V
E) 36 V

Question 12

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

A) 2.0 mH
B) 0.51 mH
C) 0.13 mH
D) 1.0 mH
E) 8.0 mH

Question 13

The stored energy in an inductor:

A) depends, in sign, upon the direction of the current
B) depends on the rate of change of current
C) is proportional to the square of the inductance
D) has units J/H
E) is none of the above

Question 14

A current of 10 A in a certain inductor results in a stored energy of 40 J. When the current is changed to 5 A in the opposite direction, the stored energy changes by:

A) 20 J
B) 30 J
C) 40 J
D) 50 J
E) 60 J