Question 1

When a switch is closed to complete a DC series RL circuit,

Accepted Answer

A)  the electric field in the wires increases to a maximum value. 
B)  the magnetic field outside the wires increases to a maximum value. 
C)  the rate of change of the electric and magnetic fields is greatest at the instant when the switch is closed. 
D)  all of the above are true. 
E)  only (a) and (c) above are true. 
A)  the electric field in the wires increases to a maximum value. 
B)  the magnetic field outside the wires increases to a maximum value. 
C)  the rate of change of the electric and magnetic fields is greatest at the instant when the switch is closed. 
D)  all of the above are true. 
E)  only (a) and (c) above are true. D

Question 2

A series LC circuit contains a 100 mH inductor, a 36.0 mF capacitor and a 12 V battery. The angular frequency of the electromagnetic oscillations in the circuit is

Accepted Answer

A)  36.0 × 10−4 rad/s. 
B)  6.00 × 10−2 rad/s. 
C)  2.78 rad/s. 
D)  16.7 rad/s. 
E)  277 rad/s. 
A)  36.0 × 10−4 rad/s. 
B)  6.00 × 10−2 rad/s. 
C)  2.78 rad/s. 
D)  16.7 rad/s. 
E)  277 rad/s. D

Question 3

A circuit contains two inductors of 6.0 mH inductance in parallel placed in series with an inductor of 8.0 mH inductance. After one of the 6.0 mH inductors burns out, the repairman wants to replace all three inductors with one inductor of equivalent inductance. Assuming inductors combine in series and parallel the same way resistors do, what inductance should he use?

Accepted Answer

A)  3.0 mH 
B)  3.4 mH 
C)  4.8 mH 
D)  11 mH 
E)  20 mH 
A)  3.0 mH 
B)  3.4 mH 
C)  4.8 mH 
D)  11 mH 
E)  20 mH D

Question 4

Coaxial Cable A has twice the length, twice the radius of the inner solid conductor, and twice the radius of the outer cylindrical conducting shell of coaxial Cable B. What is the ratio of the inductance of Cable A to that of Cable B?

Accepted Answer

A) 
  
B) 
  
C)  2 
D) 
  
E) 
  
A) 
  
B) 
  
C)  2 
D) 
  
E)

Question 5

A 10-mH inductor is connected in series with a 10-ohm resistor, a switch and a 6-volt battery. What is the time constant of the circuit? How long after the switch is closed will the current reach 99 percent of its final value?

Accepted Answer

The answer of A 10-mH inductor is connected in series...

Question 6

When a switch is closed, completing an LR series circuit, the time needed for the current to reach one half its maximum value is ____ time constants.

Accepted Answer

A)  0.250 
B)  0.500 
C)  0.693 
D)  1.00 
E)  1.44 
A)  0.250 
B)  0.500 
C)  0.693 
D)  1.00 
E)  1.44

Question 7

The switch in the figure is closed at t = 0 when the current I is zero. When I = 15 mA, what is the potential difference across the inductor?

Accepted Answer

A)  240 V 
B)  60 V 
C)  0 
D)  180 V 
E)  190 V 
A)  240 V 
B)  60 V 
C)  0 
D)  180 V 
E)  190 V

Question 8

A series LC circuit contains a 100 mH inductor, a 36.0 mF capacitor and a 12 V battery. The frequency of the electromagnetic oscillations in the circuit is

Accepted Answer

A)  5.73 × 10−4 Hz. 
B)  9.55 × 10−3 Hz. 
C)  0.442 Hz. 
D)  2.65 Hz. 
E)  44.0 Hz. 
A)  5.73 × 10−4 Hz. 
B)  9.55 × 10−3 Hz. 
C)  0.442 Hz. 
D)  2.65 Hz. 
E)  44.0 Hz.

Question 9

What is the inductance of a series RL circuit in which R = 1.0 KΩ if the current increases to one-third of its final value in 30 μs?

Accepted Answer

A)  74 mH 
B)  99 mH 
C)  49 mH 
D)  62 mH 
E)  none of the above 
A)  74 mH 
B)  99 mH 
C)  49 mH 
D)  62 mH 
E)  none of the above

Question 10

Find the magnetic energy stored in the air gap between two very large magnetic pole pieces, one North, one South, each with an area of 100 cm2. Assume the 0.05 T magnetic field is uniform within the 2-cm gap.

Accepted Answer

Question 11

After a switch is thrown to remove the battery from a DC LR circuit, but the circuit is still left complete, the time constant represents

Accepted Answer

A)  the time rate of change of the current in the circuit. 
B)  the time rate of change of the induced emf in the circuit. 
C)  the magnitude of the ratio of the current to the time rate of change of the current. 
D)  all of the above. 
E)  only (a) and (b) above. 
A)  the time rate of change of the current in the circuit. 
B)  the time rate of change of the induced emf in the circuit. 
C)  the magnitude of the ratio of the current to the time rate of change of the current. 
D)  all of the above. 
E)  only (a) and (b) above.

Question 12

A series LC circuit contains a 100 mH inductor, a 36.0 mF capacitor and a 12 V battery. The period of the electromagnetic oscillations in the circuit is

Accepted Answer

A)  0.0227 s. 
B)  0.377 s. 
C)  2.26 s. 
D)  105 s. 
E)  1750 s. 
A)  0.0227 s. 
B)  0.377 s. 
C)  2.26 s. 
D)  105 s. 
E)  1750 s.

Question 13

The figure shows an LR circuit with a switch and a 240-volt battery. At the instant the switch is closed the current in the circuit and the potential difference between points a and b, Vab, are

Accepted Answer

A)  0 A, 0 V 
B)  0 A, −240 V 
C)  0 A, +240 V 
D)  0.024 A, 0 V 
E)  0.024 A, +240 V 
A)  0 A, 0 V 
B)  0 A, −240 V 
C)  0 A, +240 V 
D)  0.024 A, 0 V 
E)  0.024 A, +240 V

Question 14

The magnetic field in a superconducting solenoid is 3.0 T. How much energy per unit volume is stored in the solenoid, in J/m3? μ0 = 4π × 10−7 T ⋅ A/m

Accepted Answer

Question 15

A circuit contains two inductors of 6.0 mH inductance in series placed in parallel with an inductor of 8.0 mH inductance. After one of the 6.0 mH inductors burns out, the repair person wants to replace all three inductors with one inductor of equivalent inductance. Assuming inductors combine in series and parallel the same way resistors do, what inductance should she use?

Accepted Answer

A)  3.0 mH 
B)  3.4 mH 
C)  4.8 mH 
D)  11 mH 
E)  20 mH 
A)  3.0 mH 
B)  3.4 mH 
C)  4.8 mH 
D)  11 mH 
E)  20 mH

Question 16

When a switch is closed, completing an LR series circuit, the time needed for the current to reach three-quarters its maximum value is ____ time constants.

Accepted Answer

A)  0.500 
B)  0.693 
C)  0.725 
D)  1.33 
E)  1.39 
A)  0.500 
B)  0.693 
C)  0.725 
D)  1.33 
E)  1.39

Question 17

An RLC circuit has L = 250 mH, C = 0.200 μF, and R = 2.00 kΩ. What is the angular frequency of its damped oscillations?

Accepted Answer

The answer of An RLC circuit has L = 250...

Question 18

An inductor produces a back emf in a DC series RL circuit when a switch connecting the battery to the circuit is closed. We can explain this by

Accepted Answer

A)  Lenz's law. 
B)  increasing magnetic flux within the coils of the inductor. 
C)  increasing current in the coils of the inductor. 
D)  all of the above. 
E)  only (a) and (c) above. 
A)  Lenz's law. 
B)  increasing magnetic flux within the coils of the inductor. 
C)  increasing current in the coils of the inductor. 
D)  all of the above. 
E)  only (a) and (c) above.

Question 19

There is no current in the circuit shown in the figure below until the switch is closed. The current through the 20-Ω resistor the instant after the switch is closed is either [1] 15 A or [2] 5.0 A, and the current through the 20-Ω resistor after the switch has been closed a long time is either [3] 5.0 A or [4] 15 A. Which combination of the above choices is correct?

Accepted Answer

A)  [1] and [3] 
B)  [1] and [4] 
C)  [2] and [3] 
D)  [2] and [4] 
E)  None of these 
A)  [1] and [3] 
B)  [1] and [4] 
C)  [2] and [3] 
D)  [2] and [4] 
E)  None of these

Question 20

If we wished to construct a "tank circuit" where electric charge originally stored on a capacitor flows through an inductor, then back again, what value of inductance should we place in series with a fully-charged 100 μF capacitor to get the circuit to resonate at 60.0 Hz?

Accepted Answer

The answer of If we wished to construct a "tank...

Exam 32: Inductance

When a switch is closed to complete a DC series RL circuit,

A series LC circuit contains a 100 mH inductor, a 36.0 mF capacitor and a 12 V battery. The angular frequency of the electromagnetic oscillations in the circuit is

Coaxial Cable A has twice the length, twice the radius of the inner solid conductor, and twice the radius of the outer cylindrical conducting shell of coaxial Cable B. What is the ratio of the inductance of Cable A to that of Cable B?

A 10-mH inductor is connected in series with a 10-ohm resistor, a switch and a 6-volt battery. What is the time constant of the circuit? How long after the switch is closed will the current reach 99 percent of its final value?

When a switch is closed, completing an LR series circuit, the time needed for the current to reach one half its maximum value is ____ time constants.

The switch in the figure is closed at t = 0 when the current I is zero. When I = 15 mA, what is the potential difference across the inductor?

A series LC circuit contains a 100 mH inductor, a 36.0 mF capacitor and a 12 V battery. The frequency of the electromagnetic oscillations in the circuit is

What is the inductance of a series RL circuit in which R = 1.0 KΩ if the current increases to one-third of its final value in 30 μs?

Find the magnetic energy stored in the air gap between two very large magnetic pole pieces, one North, one South, each with an area of 100 cm2. Assume the 0.05 T magnetic field is uniform within the 2-cm gap.

After a switch is thrown to remove the battery from a DC LR circuit, but the circuit is still left complete, the time constant represents

A series LC circuit contains a 100 mH inductor, a 36.0 mF capacitor and a 12 V battery. The period of the electromagnetic oscillations in the circuit is

The figure shows an LR circuit with a switch and a 240-volt battery. At the instant the switch is closed the current in the circuit and the potential difference between points a and b, Vab, are

The magnetic field in a superconducting solenoid is 3.0 T. How much energy per unit volume is stored in the solenoid, in J/m3? μ0 = 4π × 10−7 T ⋅ A/m

When a switch is closed, completing an LR series circuit, the time needed for the current to reach three-quarters its maximum value is ____ time constants.

An RLC circuit has L = 250 mH, C = 0.200 μF, and R = 2.00 kΩ. What is the angular frequency of its damped oscillations?

An inductor produces a back emf in a DC series RL circuit when a switch connecting the battery to the circuit is closed. We can explain this by

If we wished to construct a "tank circuit" where electric charge originally stored on a capacitor flows through an inductor, then back again, what value of inductance should we place in series with a fully-charged 100 μF capacitor to get the circuit to resonate at 60.0 Hz?

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Find the magnetic energy stored in the air gap between two very large magnetic pole pieces, one North, one South, each with an area of 100 cm². Assume the 0.05 T magnetic field is uniform within the 2-cm gap.

The figure shows an LR circuit with a switch and a 240-volt battery. At the instant the switch is closed the current in the circuit and the potential difference between points a and b, V_ab, are

The magnetic field in a superconducting solenoid is 3.0 T. How much energy per unit volume is stored in the solenoid, in J/m³? μ₀ = 4π × 10−⁷ T ⋅ A/m