Question 1

A solenoid is 15 cm long, has a radius of 5 cm, and has 400 turns. If it carries a current of 4 A, the magnetic energy stored in the solenoid is

Accepted Answer

A)   84.2 mJ
B)   0.562 J
C)   3.37 J
D)   12.6 mJ
E)   None of these is correct. A

Question 2

A long straight wire carries a constant current I. The magnitude of the magnetic flux through the illustrated rectangular loop of wire is

Accepted Answer

A)   ( μ\muμ 0/4  π\piπ ) 2Il ln(b/a) 
B)   ( μ\muμ 0/4  π\piπ ) 4Il ln(b/a) 
C)   ( μ\muμ 0/4  π\piπ ) Il ln[(a + b) /(b - a) ]
D)   ( μ\muμ 0/4  π\piπ ) 4Il ln[(b - a) /(b + a) ]
E)   ( μ\muμ 0/4  π\piπ ) 2Il ln[(b - a) /(b + a) ]  A

Question 3

The time constant for the RL circuit is of the order of a few seconds. Describe what happens to the light bulb when the switch S is closed.

Accepted Answer

A)   The light bulb comes on immediately and then goes off in a few seconds.
B)   The light bulb comes gradually in a few seconds and stays on.
C)   The light bulb does not come on at all.
D)   The light bulb comes on in a few seconds and then goes off instantaneously.
E)   The light bulb comes on in a few seconds and then goes off in a few seconds. B

Question 4

A 100-turn coil has a radius of 7.50 cm and a resistance of 50.0  $\Omega$ . At what rate must a perpendicular magnetic field change to produce a current of 5.00 A in the coil?

Accepted Answer

A)   275 T/s
B)   134 T/s
C)   329 T/s
D)   141 T/s
E)   106 T/s

Question 5

A 3.0-cm by 5.0-cm rectangular coil has 100 turns. Its axis makes an angle of 55º with a uniform magnetic field of 0.35 T. It requires 0.33 s to turn the coil until its plane is perpendicular to the magnetic field. What is the (average) magnitude of the induced EMF?

Accepted Answer

A)   0.16 V
B)   0.13 V
C)   91 mV
D)   68 mV
E)   29 mV

Question 6

A metal disk rotates about its central axis at an angular frequency of 800 radians per second in a uniform magnetic field of 0.8 T. The diameter of the disk is 8 cm. What is the magnitude of the voltage difference between the center and edge of the disk?

Accepted Answer

A)   0 V
B)   0.80 V
C)   0.51 V
D)   1.0 V
E)   3.1 V

Question 7

A 3.0-cm by 5.0-cm rectangular coil has 100 turns. Its axis makes an angle of 55º with a uniform magnetic field of 0.35 T. What is the magnetic flux through this coil?

Accepted Answer

A)   3.0*10-4 Wb
B)   4.3 * 10-4 Wb
C)   3.0 * 10-2 Wb
D)   4.3 *10-2 Wb
E)   5.3 * 10-2 Wb

Question 8

An open switch in an RL circuit is closed at time t = 0, as shown. The curve that best illustrates the variation of potential difference across the resistor as a function of time is

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   5

Question 9

A conducting loop around a bar magnet begins to move away from the magnet. Which of the following statements is true?

Accepted Answer

A)   The magnet and the loop repel one another.
B)   The magnet and the loop attract one another.
C)   The magnet is attracted, but the loop is repelled.
D)   The magnet is repelled, but the loop is attracted.
E)   The magnet and loop neither attract nor repel one another.

Question 10

A coil with a self-inductance of 6.5 H carries a current that is changing at a rate of
50 A/s. What is the induced EMF in the coil?

Accepted Answer

A)   0.13 V
B)   7.7 V
C)   32 V
D)   65 V
E)   0.32 kV

Question 11

For the two solenoids above, if l = 50 cm, N1 = N2 = 200 turns and r1 = 5 cm and r2 = 10 cm, the mutual inductance of the two solenoids is
I

Accepted Answer

A)   1.58 mH
B)   0.790 mH
C)   3.20 mH
D)   6.31 mH
E)   None of these is correct.

Question 12

A coil consisting of 20 turns of wire around the periphery of a rectangular frame 10 cm by 5.0 cm is moved from a position near a magnet where the average flux density is
1)0 mT to another position where the average is 11 mT. If this motion takes place in
1)0 s, the average EMF induced in the coil is

Accepted Answer

A)   0.10 kV
B)   1.0 kV
C)   1.0 mV
D)   0.10 MV
E)   10 mV

Question 13

A square coil of wire with side 8.0 cm and 50 turns sits in a uniform magnetic field that is perpendicular to the plane of the coil. The coil is pulled quickly out of the magnetic field in 0.2 s. If the resistance of the coil is 15 ohm and a current of 12 mA is induced in the coil, calculate the value of the magnetic field.

Accepted Answer

A)   5.6 T
B)   0.11 T
C)   7.5 * 10-3 T
D)   1.4 T
E)   9.1 T

Question 14

The plane of a wire loop with an area of 0.20 m2 is perpendicular to a magnetic field of 50 mT. In 40 ms you rotate the loop 90º so that its plane is parallel to the magnetic field. The average EMF induced in the loop is

Accepted Answer

A)   0.25 V
B)   6.0 V
C)   3.0 V
D)   4.0 V
E)   1.3 V

Question 15

After you measure the self-inductance of a coil, you unwind it and then rewind half the length of wire into a coil with the same diameter but half the number of turns. How does this change the self-inductance?

Accepted Answer

A)   it is the same
B)   it is doubled
C)   it is quadrupled
D)   it is halved
E)   it is quartered

Question 16

A uniform magnetic field of magnitude 0.5 T is parallel to the x axis. A square coil of side 10 cm has 300 turns and makes an angle of 60º with the z axis as shown. The magnetic flux through the coil is approximately

Accepted Answer

A)   0.14 Wb
B)   0.75 Wb
C)   1.5 Wb
D)   0.27 Wb
E)   0.56 Wb

Question 17

A uniform magnetic field of 0.5 T is parallel to the x axis. A square coil of side 10 cm has 300 turns and lies in the xy plane as shown. The magnetic flux through the coil is

Accepted Answer

A)   0.14 Wb
B)   0.75 Wb
C)   1.5 Wb
D)   0.27 Wb
E)   zero

Question 18

A 25-cm long conducting rod moves at a speed of 12 m/s in a plane perpendicular to a uniform magnetic field of magnitude 0.080 T. What is the induced potential difference between the ends of the rod?

Accepted Answer

A)   24 V
B)   2.4 V
C)   0.24 V
D)   0.60 kV
E)   6.0 V

Question 19

You place a coil that has 200 turns and a cross-sectional area of 0.050 m2 so that its plane is normal to a field of 3.0 T. If the field is uniformly decreased to zero in 5.0 s, what EMF is induced in the coil?

Accepted Answer

A)   0.15 kV
B)   0.12 kV
C)   6.0 V
D)   50 mV
E)   10 mV

Question 20

A rectangular surface of area 1.0 m2 is hinged along the z axis and makes an angle of 37º with the yz plane. If the local magnetic field is 10 T  , the magnetic flux through this surface is

Accepted Answer

A)   6.0 T · m2 
B)   8.0 T · m2 
C)   10 T · m2 
D)   13 T · m2 
E)   17 T · m2

Exam 8: Magnetic Induction

A solenoid is 15 cm long, has a radius of 5 cm, and has 400 turns. If it carries a current of 4 A, the magnetic energy stored in the solenoid is

The time constant for the RL circuit is of the order of a few seconds. Describe what happens to the light bulb when the switch S is closed.

A 100-turn coil has a radius of 7.50 cm and a resistance of 50.0 $\Omega$ . At what rate must a perpendicular magnetic field change to produce a current of 5.00 A in the coil?

A 3.0-cm by 5.0-cm rectangular coil has 100 turns. Its axis makes an angle of 55º with a uniform magnetic field of 0.35 T. It requires 0.33 s to turn the coil until its plane is perpendicular to the magnetic field. What is the (average) magnitude of the induced EMF?

A metal disk rotates about its central axis at an angular frequency of 800 radians per second in a uniform magnetic field of 0.8 T. The diameter of the disk is 8 cm. What is the magnitude of the voltage difference between the center and edge of the disk?

A 3.0-cm by 5.0-cm rectangular coil has 100 turns. Its axis makes an angle of 55º with a uniform magnetic field of 0.35 T. What is the magnetic flux through this coil?

An open switch in an RL circuit is closed at time t = 0, as shown. The curve that best illustrates the variation of potential difference across the resistor as a function of time is

A conducting loop around a bar magnet begins to move away from the magnet. Which of the following statements is true?

A coil with a self-inductance of 6.5 H carries a current that is changing at a rate of 50 A/s. What is the induced EMF in the coil?

For the two solenoids above, if l = 50 cm, N₁ = N₂ = 200 turns and r₁ = 5 cm and r₂ = 10 cm, the mutual inductance of the two solenoids is I

The plane of a wire loop with an area of 0.20 m² is perpendicular to a magnetic field of 50 mT. In 40 ms you rotate the loop 90º so that its plane is parallel to the magnetic field. The average EMF induced in the loop is

After you measure the self-inductance of a coil, you unwind it and then rewind half the length of wire into a coil with the same diameter but half the number of turns. How does this change the self-inductance?

A uniform magnetic field of magnitude 0.5 T is parallel to the x axis. A square coil of side 10 cm has 300 turns and makes an angle of 60º with the z axis as shown. The magnetic flux through the coil is approximately

A uniform magnetic field of 0.5 T is parallel to the x axis. A square coil of side 10 cm has 300 turns and lies in the xy plane as shown. The magnetic flux through the coil is

A 25-cm long conducting rod moves at a speed of 12 m/s in a plane perpendicular to a uniform magnetic field of magnitude 0.080 T. What is the induced potential difference between the ends of the rod?

You place a coil that has 200 turns and a cross-sectional area of 0.050 m² so that its plane is normal to a field of 3.0 T. If the field is uniformly decreased to zero in 5.0 s, what EMF is induced in the coil?

A rectangular surface of area 1.0 m² is hinged along the z axis and makes an angle of 37º with the yz plane. If the local magnetic field is 10 T , the magnetic flux through this surface is

Exam 8: Magnetic Induction

A solenoid is 15 cm long, has a radius of 5 cm, and has 400 turns. If it carries a current of 4 A, the magnetic energy stored in the solenoid is

A long straight wire carries a constant current I. The magnitude of the magnetic flux through the illustrated rectangular loop of wire is

The time constant for the RL circuit is of the order of a few seconds. Describe what happens to the light bulb when the switch S is closed.

A 100-turn coil has a radius of 7.50 cm and a resistance of 50.0 Ω\OmegaΩ . At what rate must a perpendicular magnetic field change to produce a current of 5.00 A in the coil?

A 3.0-cm by 5.0-cm rectangular coil has 100 turns. Its axis makes an angle of 55º with a uniform magnetic field of 0.35 T. It requires 0.33 s to turn the coil until its plane is perpendicular to the magnetic field. What is the (average) magnitude of the induced EMF?

A metal disk rotates about its central axis at an angular frequency of 800 radians per second in a uniform magnetic field of 0.8 T. The diameter of the disk is 8 cm. What is the magnitude of the voltage difference between the center and edge of the disk?

A 3.0-cm by 5.0-cm rectangular coil has 100 turns. Its axis makes an angle of 55º with a uniform magnetic field of 0.35 T. What is the magnetic flux through this coil?

An open switch in an RL circuit is closed at time t = 0, as shown. The curve that best illustrates the variation of potential difference across the resistor as a function of time is

A conducting loop around a bar magnet begins to move away from the magnet. Which of the following statements is true?

A coil with a self-inductance of 6.5 H carries a current that is changing at a rate of 50 A/s. What is the induced EMF in the coil?

For the two solenoids above, if l = 50 cm, N1 = N2 = 200 turns and r1 = 5 cm and r2 = 10 cm, the mutual inductance of the two solenoids is I

The plane of a wire loop with an area of 0.20 m2 is perpendicular to a magnetic field of 50 mT. In 40 ms you rotate the loop 90º so that its plane is parallel to the magnetic field. The average EMF induced in the loop is

After you measure the self-inductance of a coil, you unwind it and then rewind half the length of wire into a coil with the same diameter but half the number of turns. How does this change the self-inductance?

A uniform magnetic field of magnitude 0.5 T is parallel to the x axis. A square coil of side 10 cm has 300 turns and makes an angle of 60º with the z axis as shown. The magnetic flux through the coil is approximately

A uniform magnetic field of 0.5 T is parallel to the x axis. A square coil of side 10 cm has 300 turns and lies in the xy plane as shown. The magnetic flux through the coil is

A 25-cm long conducting rod moves at a speed of 12 m/s in a plane perpendicular to a uniform magnetic field of magnitude 0.080 T. What is the induced potential difference between the ends of the rod?

You place a coil that has 200 turns and a cross-sectional area of 0.050 m2 so that its plane is normal to a field of 3.0 T. If the field is uniformly decreased to zero in 5.0 s, what EMF is induced in the coil?

A rectangular surface of area 1.0 m2 is hinged along the z axis and makes an angle of 37º with the yz plane. If the local magnetic field is 10 T , the magnetic flux through this surface is

A 100-turn coil has a radius of 7.50 cm and a resistance of 50.0 $\Omega$ . At what rate must a perpendicular magnetic field change to produce a current of 5.00 A in the coil?

For the two solenoids above, if l = 50 cm, N₁ = N₂ = 200 turns and r₁ = 5 cm and r₂ = 10 cm, the mutual inductance of the two solenoids is I

The plane of a wire loop with an area of 0.20 m² is perpendicular to a magnetic field of 50 mT. In 40 ms you rotate the loop 90º so that its plane is parallel to the magnetic field. The average EMF induced in the loop is

You place a coil that has 200 turns and a cross-sectional area of 0.050 m² so that its plane is normal to a field of 3.0 T. If the field is uniformly decreased to zero in 5.0 s, what EMF is induced in the coil?

A rectangular surface of area 1.0 m² is hinged along the z axis and makes an angle of 37º with the yz plane. If the local magnetic field is 10 T , the magnetic flux through this surface is