Question 1

In the figure, two solenoids are side by side. The switch S, initially open, is closed. The induced current through the resistor R is

Accepted Answer

A)  from a to b. 
B)  from b to a. 
C)  There is no induced current through the resistor. 
A)  from a to b. 
B)  from b to a. 
C)  There is no induced current through the resistor.

Question 2

For a long ideal solenoid having a circular cross-section, the magnetic field strength within the solenoid is given by the equation B(t) = 5.0t T, where t is time in seconds. If the induced electric field outside the solenoid is 1.1 V/m at a distance of 2.0 m from the axis of the solenoid, find the radius of the solenoid.

Accepted Answer

A)  0.30 m 
B)  77 m 
C)  0.94 m 
D)  9.0 m 
A)  0.30 m 
B)  77 m 
C)  0.94 m 
D)  9.0 m

Question 3

A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the direction of the induced current in this coil as the field fades?

Accepted Answer

A)  counter-clockwise then clockwise 
B)  clockwise then counter-clockwise 
C)  clockwise 
D)  counter-clockwise 
E)  There is no current induced in the coil. 
A)  counter-clockwise then clockwise 
B)  clockwise then counter-clockwise 
C)  clockwise 
D)  counter-clockwise 
E)  There is no current induced in the coil.

Question 4

A rectangular coil having N turns and measuring 15 cm by 25 cm is rotating in a uniform 1.6-T magnetic field with a frequency of 75 Hz. The rotation axis is perpendicular to the direction of the field. If the coil develops a sinusoidal emf of maximum value 56.9 V, what is the value of N?

Accepted Answer

A)  2 
B)  4 
C)  6 
D)  8 
E)  10 
A)  2 
B)  4 
C)  6 
D)  8 
E)  10

Question 5

The figure shows three metal coils labeled A, B, and C heading towards a region where a uniform static magnetic field exists. The coils move with the same constant velocity and all have the same resistance. Their relative sizes are indicated by the background grid. As they enter the magnetic field the coils will have an induced electric current in them. For which coil will the current be the greatest?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  The current is the same in all three cases since all the coils move with the same velocity. 
E)  There is no induced current in any of the coils since they move at constant velocity. 
A)  A 
B)  B 
C)  C 
D)  The current is the same in all three cases since all the coils move with the same velocity. 
E)  There is no induced current in any of the coils since they move at constant velocity.

Question 6

What is the self-inductance of a solenoid 30.0 cm long having 100 turns of wire and a cross-sectional area of 1.00 × 10-4 m2? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  4.19 nH 
B)  4.19 pH 
C)  4.19 µH 
D)  4.19 mH 
E)  4.19 H 
A)  4.19 nH 
B)  4.19 pH 
C)  4.19 µH 
D)  4.19 mH 
E)  4.19 H

Exam 33: Electromagnetic Induction

In the figure, two solenoids are side by side. The switch S, initially open, is closed. The induced current through the resistor R is

A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the direction of the induced current in this coil as the field fades?

A rectangular coil having N turns and measuring 15 cm by 25 cm is rotating in a uniform 1.6-T magnetic field with a frequency of 75 Hz. The rotation axis is perpendicular to the direction of the field. If the coil develops a sinusoidal emf of maximum value 56.9 V, what is the value of N?

What is the self-inductance of a solenoid 30.0 cm long having 100 turns of wire and a cross-sectional area of 1.00 × 10-4 m2? (μ0 = 4π × 10-7 T ∙ m/A)

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What is the self-inductance of a solenoid 30.0 cm long having 100 turns of wire and a cross-sectional area of 1.00 × 10^-4 m²? (μ₀ = 4π × 10^-7 T ∙ m/A)