Question 1

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

Question 2

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

Question 3

A 6.0 mH inductor is in a series circuit with a resistor and an ideal battery.At the instant the current in the circuit is 5.0 A the energy stored in the inductor is:

Accepted Answer

A) 0 J 
B) 7.5*10-2 J 
C) 15* 10-2 J 
D) 30 *10-2 J 
E) unknown since the rate of change of the current is not given 
A) 0 J 
B) 7.5*10-2 J 
C) 15* 10-2 J 
D) 30 *10-2 J 
E) unknown since the rate of change of the current is not given B

Question 4

1 weber is the same as:

Accepted Answer

A) 1 V/s 
B) 1 T/s 
C) 1 T/m 
D) 1 T.m2 
E) 1 T/m2 
A) 1 V/s 
B) 1 T/s 
C) 1 T/m 
D) 1 T.m2 
E) 1 T/m2

Question 5

The emf that appears in Faraday's law is:

Accepted Answer

A) around a conducting circuit 
B) around the boundary of the surface used to compute the magnetic flux 
C) throughout the surface used to compute the magnetic flux 
D) perpendicular to the surface used to compute the magnetic flux 
E) none of the above 
A) around a conducting circuit 
B) around the boundary of the surface used to compute the magnetic flux 
C) throughout the surface used to compute the magnetic flux 
D) perpendicular to the surface used to compute the magnetic flux 
E) none of the above

Question 6

Immediately after switch S in the circuit shown is closed, the current through the battery is:

Accepted Answer

A) 0 
B) V0/R1 
C) V0/R2 
D) V0/(R1 + R2) 
E) V0(R1 + R2)/(R1R2) 
A) 0 
B) V0/R1 
C) V0/R2 
D) V0/(R1 + R2) 
E) V0(R1 + R2)/(R1R2)

Question 7

Two coils have a mutual inductance of 3.5 mH.If the current in one coil is changing at a rate of 4.8 A/s, what is the emf induced in the second coil?

Accepted Answer

A) 7.3 x 10-4 V 
B) 0.017 V 
C) 1400 V 
D) cannot tell without knowing the inductance of the second coil 
E) cannot tell without knowing the current in the second coil 
A) 7.3 x 10-4 V 
B) 0.017 V 
C) 1400 V 
D) cannot tell without knowing the inductance of the second coil 
E) cannot tell without knowing the current in the second coil

Question 8

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:

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

Question 9

A merry-go-round has an area of 300 m2 and spins at 2 rpm about a vertical axis at a place where the Earth's magnetic field is vertical and has a magnitude of 5 *10-5 T.The emf around the rim is:

Accepted Answer

A) 0 V 
B) 0.5 mV 
C) 3.1 mV 
D) 15 mV 
E) 190 mV 
A) 0 V 
B) 0.5 mV 
C) 3.1 mV 
D) 15 mV 
E) 190 mV

Question 10

A long straight wire is in the plane of a rectangular conducting loop.The straight wire carries a constant current i, as shown.While the wire is being moved toward the loop, the current in the loop is:

Accepted Answer

A) zero 
B) clockwise 
C) counterclockwise 
D) clockwise in the left side and counterclockwise in the right side 
E) counterclockwise in the left side and clockwise in the right side 
A) zero 
B) clockwise 
C) counterclockwise 
D) clockwise in the left side and counterclockwise in the right side 
E) counterclockwise in the left side and clockwise in the right side

Question 11

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

Question 12

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:

Accepted Answer

A) 0 A/s 
B) 0.5 A/s 
C) 50 A/s 
D) 250 A/s 
E) 500 A/s 
A) 0 A/s 
B) 0.5 A/s 
C) 50 A/s 
D) 250 A/s 
E) 500 A/s

Question 13

An inductor with inductance L and an inductor with inductance 2L are connected in parallel.When the rate of change of the current in the larger inductor is 2000 A/s the rate of change of the current in the smaller is:

Accepted Answer

A) 400 A/s 
B) 1000 A/s 
C) 1600 A/s 
D) 2000 A/s 
E) 4000 A/s 
A) 400 A/s 
B) 1000 A/s 
C) 1600 A/s 
D) 2000 A/s 
E) 4000 A/s

Question 14

A square loop of wire lies in the plane of the page.A decreasing magnetic field is directed into the page.The induced current in the loop is:

Accepted Answer

A) counterclockwise 
B) clockwise 
C) zero 
D) up the left edge and from right to left along the top edge 
E) through the middle of the page 
A) counterclockwise 
B) clockwise 
C) zero 
D) up the left edge and from right to left along the top edge 
E) through the middle of the page

Question 15

In the experiment shown:

Accepted Answer

A) there is a steady reading in G as long as S is closed 
B) a motional emf is generated when S is closed 
C) the current in the battery goes through G 
D) there is a current in G just after S is opened or closed 
E) since the two loops are not connected, the current in G is always zero 
A) there is a steady reading in G as long as S is closed 
B) a motional emf is generated when S is closed 
C) the current in the battery goes through G 
D) there is a current in G just after S is opened or closed 
E) since the two loops are not connected, the current in G is always zero

Question 16

The stored energy in an inductor:

Accepted Answer

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 
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 17

A car travels northward at 75 km/h along a straight road in a region where Earth's magnetic field has a vertical component of 0.50*10-4 T.The emf induced between the left and right side, separated by 1.7 m, is:

Accepted Answer

A) 0 V 
B) 1.8 mV 
C) 3.6 mV 
D) 6.4 mV 
E) 23 mV 
A) 0 V 
B) 1.8 mV 
C) 3.6 mV 
D) 6.4 mV 
E) 23 mV

Question 18

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) zero 
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

Question 19

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

Question 20

An inductance L and a resistance R are connected in series to an ideal battery.A switch in the circuit is closed at time t = 0, at which time the current is zero.The rate of increase of the energy stored in the inductor is a maximum:

Accepted Answer

A) just after the switch is closed 
B) at the time t = L/R after the switch is closed 
C) at the time t = 2L/R after the switch is closed 
D) at the time t = (L/R)ln 2 after the switch is closed 
E) a long time after the switch is closed 
A) just after the switch is closed 
B) at the time t = L/R after the switch is closed 
C) at the time t = 2L/R after the switch is closed 
D) at the time t = (L/R)ln 2 after the switch is closed 
E) a long time after the switch is closed

Exam 30: Induction and Inductance

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

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 6.0 mH inductor is in a series circuit with a resistor and an ideal battery.At the instant the current in the circuit is 5.0 A the energy stored in the inductor is:

1 weber is the same as:

The emf that appears in Faraday's law is:

Immediately after switch S in the circuit shown is closed, the current through the battery is:

Two coils have a mutual inductance of 3.5 mH.If the current in one coil is changing at a rate of 4.8 A/s, what is the emf induced in the second coil?

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:

A merry-go-round has an area of 300 m2 and spins at 2 rpm about a vertical axis at a place where the Earth's magnetic field is vertical and has a magnitude of 5 *10-5 T.The emf around the rim is:

A long straight wire is in the plane of a rectangular conducting loop.The straight wire carries a constant current i, as shown.While the wire is being moved toward the loop, the current in the loop is:

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 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:

An inductor with inductance L and an inductor with inductance 2L are connected in parallel.When the rate of change of the current in the larger inductor is 2000 A/s the rate of change of the current in the smaller is:

A square loop of wire lies in the plane of the page.A decreasing magnetic field is directed into the page.The induced current in the loop is:

In the experiment shown:

The stored energy in an inductor:

A car travels northward at 75 km/h along a straight road in a region where Earth's magnetic field has a vertical component of 0.50*10-4 T.The emf induced between the left and right side, separated by 1.7 m, is:

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

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:

An inductance L and a resistance R are connected in series to an ideal battery.A switch in the circuit is closed at time t = 0, at which time the current is zero.The rate of increase of the energy stored in the inductor is a maximum:

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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:

A merry-go-round has an area of 300 m² and spins at 2 rpm about a vertical axis at a place where the Earth's magnetic field is vertical and has a magnitude of 5 *10^-5 T.The emf around the rim is:

A car travels northward at 75 km/h along a straight road in a region where Earth's magnetic field has a vertical component of 0.50*10^-4 T.The emf induced between the left and right side, separated by 1.7 m, is: