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) 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 straight conductor 10 cm long is perpendicular to a uniform magnetic field of flux density 2.0 mT.When the conductor carries a current of 5.0 A,the force exerted on it by the field is

Accepted Answer

A) 0.25 kN 
B) 40 $\mu$N 
C) 1.0 mN 
D) zero 
E) 5.0 mN 
A) 0.25 kN 
B) 40 $\mu$N 
C) 1.0 mN 
D) zero 
E) 5.0 mN C

Question 3

A solenoid 50 cm long with a radius of 5.0 cm has 800 turns.You find that it carries a current of 10 A.The magnetic flux through it is approximately

Accepted Answer

A) 47 mWb 
B) 31 mWb 
C) 98 mWb 
D) 18 mWb 
E) 67 mWb 
A) 47 mWb 
B) 31 mWb 
C) 98 mWb 
D) 18 mWb 
E) 67 mWb C

Question 4

For the current in a stationary circuit to induce a current in an independent stationary circuit,it is necessary for the first circuit to have

Accepted Answer

A) a steady current. 
B) a large current. 
C) no current. 
D) a changing current. 
E) None of these is correct. 
A) a steady current. 
B) a large current. 
C) no current. 
D) a changing current. 
E) None of these is correct.

Question 5

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

Question 6

The magnetic flux through a 50-cm-long solenoid that has 500 turns of radius 3.0 cm is 3.0 $\times$ 10-2 Wb.Calculate the current through the solenoid.

Accepted Answer

A) 53 A 
B) 5.4 A 
C) 17 A 
D) 1.3 A 
E) 34 A 
A) 53 A 
B) 5.4 A 
C) 17 A 
D) 1.3 A 
E) 34 A

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

Question 8

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

Question 9

Use the following figure for the next problem.  
-A rectangle is bent on two sides at 90S1U1P1$\circ$S1S1P0 so that one end lies along the xy plane while the other end lies along the xz plane.The length a = 10 cm and b = 30 cm.A magnetic field of strength B = 0.1 T lies in the yz plane and points at an angle $\theta$ = 30S1U1P1$\circ$S1S1P0 with the y axis.The flux through the rectangle is

Accepted Answer

A) 52.0 mWb 
B) 30.0 mWb 
C) 41.0 mWb 
D) 60.0 mWb 
E) None of these is correct. 
A) 52.0 mWb 
B) 30.0 mWb 
C) 41.0 mWb 
D) 60.0 mWb 
E) None of these is correct.

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

Question 11

Suppose you double the magnetic field in a given region and quadruple the area through which this magnetic field exists.The effect on the flux through this area would be to

Accepted Answer

A) leave it unchanged. 
B) double it. 
C) quadruple it. 
D) increase it by a factor of six. 
E) increase it by a factor of eight. 
A) leave it unchanged. 
B) double it. 
C) quadruple it. 
D) increase it by a factor of six. 
E) increase it by a factor of eight.

Question 12

Use the following figure for the next problem.  
-A rectangle is bent on two sides at 90S1U1P1$\circ$S1S1P0 so that one end lies along the xy-plane while the other end lies along the xz-plane.The length a = 10 cm and b = 30 cm.At t = 0,a magnetic field of strength B = 0.1 T lies in the yz-plane and points at an angle $\theta$ = 30S1U1P1$\circ$S1S1P0 and 10 ms later the field points in the opposite direction.The EMF induced in the rectangle is

Accepted Answer

A) 10.4 V 
B) 6.0 V 
C) 12 V 
D) 8.2 V 
E) None of these is correct. 
A) 10.4 V 
B) 6.0 V 
C) 12 V 
D) 8.2 V 
E) None of these is correct.

Question 13

Eddy currents

Accepted Answer

A) are a consequence of changing magnetic flux. 
B) generate heat and result in power loss. 
C) can be used for damping and braking purposes. 
D) are described by both Faraday's and Lenz's laws. 
E) All of these are correct. 
A) are a consequence of changing magnetic flux. 
B) generate heat and result in power loss. 
C) can be used for damping and braking purposes. 
D) are described by both Faraday's and Lenz's laws. 
E) All of these are correct.

Question 14

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

Question 15

The self-inductance of a wire coil is a proportionality constant that relates

Accepted Answer

A) electric field to current. 
B) electric flux to current. 
C) magnetic flux to current. 
D) magnetic field to current. 
E) voltage to current. 
A) electric field to current. 
B) electric flux to current. 
C) magnetic flux to current. 
D) magnetic field to current. 
E) voltage to current.

Question 16

A coil of self inductance 7.5 mH and resistance of 30 $\Omega$ is placed across the terminals of a 12-V battery of negligible internal resistance.The current in this circuit after 50 $\mu$s is approximately

Accepted Answer

A) 73 mA 
B) 47 mA 
C) 28 mA 
D) 51 mA 
E) 19 mA 
A) 73 mA 
B) 47 mA 
C) 28 mA 
D) 51 mA 
E) 19 mA

Question 17

How many turns are needed in a solenoid of radius 10 cm and length 20 cm for its self-inductance to be 6.0 H?

Accepted Answer

A) 30 
B) 74 
C) 500 
D) 550 
E) 5500 
A) 30 
B) 74 
C) 500 
D) 550 
E) 5500

Question 18

What is the average induced EMF between the ends of the wings of a plane flying at a speed of 500 km/hr when the vertical component of Earth's magnetic field is 3 $\times$ 10-5 T? The distance between the wingtips is 25 m.

Accepted Answer

A) 0.20 V 
B) 0.050 V 
C) 6.0 V 
D) 0.10 V 
E) none of the above 
A) 0.20 V 
B) 0.050 V 
C) 6.0 V 
D) 0.10 V 
E) none of the above

Question 19

A square coil of wire with side 9.0 cm and 8 turns sits in a uniform magnetic field of 2 T that is perpendicular to the plane of the coil.If an EMF of 0.5 V is induced in the coil when the magnetic field is reversed,find the time taken for the field reversal.

Accepted Answer

A) 0.26 s 
B) 1.0 s 
C) 5.8 s 
D) 1.6 s 
E) 0.52 s 
A) 0.26 s 
B) 1.0 s 
C) 5.8 s 
D) 1.6 s 
E) 0.52 s

Question 20

Which of the following statements about superconductors is true?

Accepted Answer

A) Both type I and type II superconductors have zero resistance below the critical temperature Tc. 
B) In type I superconductors,the magnetic is expelled from the superconductors below the critical temperature Tc. 
C) In type II superconductors,the magnetic is expelled from the superconductors below the critical temperature Tc and below a certain field Bc1. 
D) Superconductors are prefect diamagnetics. 
E) All the above statements are true. 
A) Both type I and type II superconductors have zero resistance below the critical temperature Tc. 
B) In type I superconductors,the magnetic is expelled from the superconductors below the critical temperature Tc. 
C) In type II superconductors,the magnetic is expelled from the superconductors below the critical temperature Tc and below a certain field Bc1. 
D) Superconductors are prefect diamagnetics. 
E) All the above statements are true.

Exam 28: 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 straight conductor 10 cm long is perpendicular to a uniform magnetic field of flux density 2.0 mT.When the conductor carries a current of 5.0 A,the force exerted on it by the field is

A solenoid 50 cm long with a radius of 5.0 cm has 800 turns.You find that it carries a current of 10 A.The magnetic flux through it is approximately

For the current in a stationary circuit to induce a current in an independent stationary circuit,it is necessary for the first circuit to have

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

The magnetic flux through a 50-cm-long solenoid that has 500 turns of radius 3.0 cm is 3.0 ×\times× 10-2 Wb.Calculate the current through the solenoid.

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 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?

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?

Suppose you double the magnetic field in a given region and quadruple the area through which this magnetic field exists.The effect on the flux through this area would be to

Eddy currents

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?

The self-inductance of a wire coil is a proportionality constant that relates

A coil of self inductance 7.5 mH and resistance of 30 Ω\OmegaΩ is placed across the terminals of a 12-V battery of negligible internal resistance.The current in this circuit after 50 μ\muμ s is approximately

How many turns are needed in a solenoid of radius 10 cm and length 20 cm for its self-inductance to be 6.0 H?

What is the average induced EMF between the ends of the wings of a plane flying at a speed of 500 km/hr when the vertical component of Earth's magnetic field is 3 ×\times× 10-5 T? The distance between the wingtips is 25 m.

A square coil of wire with side 9.0 cm and 8 turns sits in a uniform magnetic field of 2 T that is perpendicular to the plane of the coil.If an EMF of 0.5 V is induced in the coil when the magnetic field is reversed,find the time taken for the field reversal.

Which of the following statements about superconductors is true?

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Filters

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

The magnetic flux through a 50-cm-long solenoid that has 500 turns of radius 3.0 cm is 3.0 $\times$ 10^-2 Wb.Calculate the current through the solenoid.

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 coil of self inductance 7.5 mH and resistance of 30 $\Omega$ is placed across the terminals of a 12-V battery of negligible internal resistance.The current in this circuit after 50 $\mu$ s is approximately

What is the average induced EMF between the ends of the wings of a plane flying at a speed of 500 km/hr when the vertical component of Earth's magnetic field is 3 $\times$ 10^-5 T? The distance between the wingtips is 25 m.