Question 1

In the diagram, assume that all the magnetic field lines generated by coil 1 pass through coil 2.Coil 1 has 100 turns and coil 2 has 400 turns.Then:

Accepted Answer

A) the currents will be the same in the two coils 
B) the emf around coil 1 will be 1/4 the emf around coil 2 
C) the current in coil 1 will be 1/4 the current in coil 2 
D) the emfs will be the same in the two coils 
E) none of the above 
A) the currents will be the same in the two coils 
B) the emf around coil 1 will be 1/4 the emf around coil 2 
C) the current in coil 1 will be 1/4 the current in coil 2 
D) the emfs will be the same in the two coils 
E) none of the above

Question 2

1 weber is the same as:

Accepted Answer

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

Question 3

A rectangular loop of wire has area A.It is placed perpendicular to a uniform magnetic field B and then spun around one of its sides at frequency f.The maximum induced emf is:

Accepted Answer

A) BAf/2π 
B) BAf 
C) 2BAf 
D) 2$\mu$BAf 
E) 4$\mu$BAf 
A) BAf/2π 
B) BAf 
C) 2BAf 
D) 2$\mu$BAf 
E) 4$\mu$BAf

Question 4

The circuit shown is in a uniform magnetic field that is into the page.The current in the circuit is 0.20 A.At what rate is the magnitude of the magnetic field changing? Is it increasing or decreasing?

Accepted Answer

A) 0 T/s 
B) 140 T/s, decreasing 
C) 140 T/s, increasing 
D) 420 T/s, decreasing 
E) 420 T/s, increasing 
A) 0 T/s 
B) 140 T/s, decreasing 
C) 140 T/s, increasing 
D) 420 T/s, decreasing 
E) 420 T/s, increasing

Question 5

A 3.5 mH inductor and a 4.5 mH inductor are connected in series.The equivalent inductance is:

Accepted Answer

A) 0.13 mH 
B) 0.51 mH 
C) 1.0 mH 
D) 2.0 mH 
E) 8.0 mH 
A) 0.13 mH 
B) 0.51 mH 
C) 1.0 mH 
D) 2.0 mH 
E) 8.0 mH

Question 6

The emf developed in a coil X due to the current in a neighboring coil Y is proportional to the:

Accepted Answer

A) magnetic field in X 
B) rate of change of magnetic field in X 
C) resistance of X 
D) thickness of the wire in X 
E) current in Y 
A) magnetic field in X 
B) rate of change of magnetic field in X 
C) resistance of X 
D) thickness of the wire in X 
E) current in Y

Question 7

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel.When the total emf of the combination is 16 V, the rate of change of the current in the larger inductor is:

Accepted Answer

A) 2.0 * 103 A/s 
B) 3.6 *103 A/s 
C) 4.6 * 103 A/s 
D) 7.0 * 103 A/s 
E) 8.1 *103 A/s 
A) 2.0 * 103 A/s 
B) 3.6 *103 A/s 
C) 4.6 * 103 A/s 
D) 7.0 * 103 A/s 
E) 8.1 *103 A/s

Question 8

A rod lies across frictionless rails in a uniform magnetic field B, as shown.The rod moves to the right with speed v.In order for the emf around the circuit to be zero, the magnitude of the magnetic field should:

Accepted Answer

A) not change 
B) increase linearly with time 
C) decrease linearly with time 
D) increase quadratically with time 
E) decrease quadratically with time 
A) not change 
B) increase linearly with time 
C) decrease linearly with time 
D) increase quadratically with time 
E) decrease quadratically with time

Question 9

The four wire loops shown have edge lengths of either L, 2L, or 3L.They will move with the same speed into a region of uniform magnetic field directed out of the page.Rank them according to the maximum magnitude of the induced emf, least to greatest.

Accepted Answer

A) 1 and 2 tie, then 3 and 4 tie 
B) 3 and 4 tie, then 1 and 2 tie 
C) 4, then 2 and 3 tie, then 1 
D) 1, then 2 and 3 tie, then 4 
E) 1, 2, 3, 4 
A) 1 and 2 tie, then 3 and 4 tie 
B) 3 and 4 tie, then 1 and 2 tie 
C) 4, then 2 and 3 tie, then 1 
D) 1, then 2 and 3 tie, then 4 
E) 1, 2, 3, 4

Question 10

A current of 10 A in a certain inductor results in a stored energy of 40 J.When the current is changed to 5 A in the opposite direction, the stored energy changes by:

Accepted Answer

A) 20 J 
B) 30 J 
C) 40 J 
D) 50 J 
E) 60 J 
A) 20 J 
B) 30 J 
C) 40 J 
D) 50 J 
E) 60 J

Question 11

A rod of length L and electrical resistance R moves through a constant uniform magnetic field ; both the magnetic field and the direction of motion are parallel to the rod.The force that must be applied by a person to keep the rod moving with constant velocity is:

Accepted Answer

A) 0 
B) BLv 
C) BLv/R 
D) B2L2v/R 
E) B2L2v2/R 
A) 0 
B) BLv 
C) BLv/R 
D) B2L2v/R 
E) B2L2v2/R

Question 12

At a particular instant of time the total magnetic flux through a stationary conducting loop is less in magnitude than the flux associated with an externally applied field.This might occur because:

Accepted Answer

A) the applied field is normal to the loop and increasing in magnitude 
B) the applied field is normal to the loop and decreasing in magnitude 
C) the applied field is parallel to the plane of the loop and increasing in magnitude 
D) the applied field is parallel to the plane of the loop and decreasing in magnitude 
E) the applied field is tangent to the loop 
A) the applied field is normal to the loop and increasing in magnitude 
B) the applied field is normal to the loop and decreasing in magnitude 
C) the applied field is parallel to the plane of the loop and increasing in magnitude 
D) the applied field is parallel to the plane of the loop and decreasing in magnitude 
E) the applied field is tangent to the loop

Question 13

A 0.20-cm radius cylinder, 3.0 cm long, is wrapped with wire to form an inductor.At the instant the magnetic field in the interior is 5.0 mT, the energy stored in the field is:

Accepted Answer

A) 0 J 
B) 3.8 * 10-6 J 
C) 7.5 * 10-6 J 
D) 7.5 * 10-4 J 
E) 9.9 J 
A) 0 J 
B) 3.8 * 10-6 J 
C) 7.5 * 10-6 J 
D) 7.5 * 10-4 J 
E) 9.9 J

Question 14

A cylindrical region of radius R contains a uniform magnetic field, parallel to its axis, with magnitude that is changing linearly with time.If r is the radial distance from the cylinder axis, the magnitude of the induced electric field inside the cylindrical region is proportional to:

Accepted Answer

A) R 
B) r 
C) r2 
D) 1/r 
E) 1/r2 
A) R 
B) r 
C) r2 
D) 1/r 
E) 1/r2

Question 15

Which statement about eddy currents is false?

Accepted Answer

A) They can be prevented by cutting a slot in a solid conducting plate, to prevent electrons from being able to make a complete circuit. 
B) The mechanical energy that is lost when eddy currents are created returns when the eddy currents cease. 
C) They can be used as a passive braking system, as no external power source is needed if permanent magnets are used. 
D) They are created in solid conducting plates as they move in and out of magnetic fields. 
E) The faster the conductor moves, the larger the eddy currents will be. 
A) They can be prevented by cutting a slot in a solid conducting plate, to prevent electrons from being able to make a complete circuit. 
B) The mechanical energy that is lost when eddy currents are created returns when the eddy currents cease. 
C) They can be used as a passive braking system, as no external power source is needed if permanent magnets are used. 
D) They are created in solid conducting plates as they move in and out of magnetic fields. 
E) The faster the conductor moves, the larger the eddy currents will be.

Question 16

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 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 = L/R2 after the switch is closed 
D) at the time t = 2L/R 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 = L/R2 after the switch is closed 
D) at the time t = 2L/R after the switch is closed 
E) a long time after the switch is closed

Question 17

A flat coil of wire, having 5 turns, has an inductance L.The inductance of a similar coil having 20 turns is:

Accepted Answer

A) 4L 
B) L/4 
C) 16L 
D) L/16 
E) L 
A) 4L 
B) L/4 
C) 16L 
D) L/16 
E) L

Question 18

A 3.5 mH inductor and a 4.5 mH inductor are connected in series and a time varying current is established in them.When the total emf of the combination is 16 V, the emf of the larger inductor is:

Accepted Answer

A) 2.3 V 
B) 7.0 V 
C) 9.0 V 
D) 28 V 
E) 36 V 
A) 2.3 V 
B) 7.0 V 
C) 9.0 V 
D) 28 V 
E) 36 V

Question 19

The quantity (B2/$\mu$o)has units of:

Accepted Answer

A) J 
B) J/H 
C) J/m 
D) J/m3 
E) H/m3 
A) J 
B) J/H 
C) J/m 
D) J/m3 
E) H/m3

Question 20

In each of the following operations, energy is expended.The LEAST percentage of returnable electrical energy will be yielded by:

Accepted Answer

A) charging a capacitor 
B) charging a storage battery 
C) sending current through a resistor 
D) establishing a current through an inductor 
E) moving a conducting rod through a magnetic field 
A) charging a capacitor 
B) charging a storage battery 
C) sending current through a resistor 
D) establishing a current through an inductor 
E) moving a conducting rod through a magnetic field

Exam 30: Induction and Inductance

In the diagram, assume that all the magnetic field lines generated by coil 1 pass through coil 2.Coil 1 has 100 turns and coil 2 has 400 turns.Then:

1 weber is the same as:

A rectangular loop of wire has area A.It is placed perpendicular to a uniform magnetic field B and then spun around one of its sides at frequency f.The maximum induced emf is:

The circuit shown is in a uniform magnetic field that is into the page.The current in the circuit is 0.20 A.At what rate is the magnitude of the magnetic field changing? Is it increasing or decreasing?

A 3.5 mH inductor and a 4.5 mH inductor are connected in series.The equivalent inductance is:

The emf developed in a coil X due to the current in a neighboring coil Y is proportional to the:

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel.When the total emf of the combination is 16 V, the rate of change of the current in the larger inductor is:

A rod lies across frictionless rails in a uniform magnetic field B, as shown.The rod moves to the right with speed v.In order for the emf around the circuit to be zero, the magnitude of the magnetic field should:

The four wire loops shown have edge lengths of either L, 2L, or 3L.They will move with the same speed into a region of uniform magnetic field directed out of the page.Rank them according to the maximum magnitude of the induced emf, least to greatest.

A current of 10 A in a certain inductor results in a stored energy of 40 J.When the current is changed to 5 A in the opposite direction, the stored energy changes by:

A rod of length L and electrical resistance R moves through a constant uniform magnetic field ; both the magnetic field and the direction of motion are parallel to the rod.The force that must be applied by a person to keep the rod moving with constant velocity is:

At a particular instant of time the total magnetic flux through a stationary conducting loop is less in magnitude than the flux associated with an externally applied field.This might occur because:

A 0.20-cm radius cylinder, 3.0 cm long, is wrapped with wire to form an inductor.At the instant the magnetic field in the interior is 5.0 mT, the energy stored in the field is:

A cylindrical region of radius R contains a uniform magnetic field, parallel to its axis, with magnitude that is changing linearly with time.If r is the radial distance from the cylinder axis, the magnitude of the induced electric field inside the cylindrical region is proportional to:

Which statement about eddy currents is false?

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 energy stored in the inductor is a maximum:

A flat coil of wire, having 5 turns, has an inductance L.The inductance of a similar coil having 20 turns is:

A 3.5 mH inductor and a 4.5 mH inductor are connected in series and a time varying current is established in them.When the total emf of the combination is 16 V, the emf of the larger inductor is:

The quantity (B2/ μ\muμ o)has units of:

In each of the following operations, energy is expended.The LEAST percentage of returnable electrical energy will be yielded by:

Measurement

Motion Along a Straight Line

Vector

Motion in Two and Three Dimensions

Force and Motion I

Force and Motion II

Kinetic Energy and Work

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

Gravitation

Fluids

Oscillations

Waves I

Waves II

Temperature, Heat, and the First Law of Thermodynamics

The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Electric Charge

Electric Fields

Gauss Law

Electric Potential

Capacitance

Current and Resistance

Circuits

Magnetic Fields

Magnetic Fields Due to Currents

Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

Electromagnetic Waves

Images

Interference

Diffraction

Relativity

Photons and Matter Waves

More About Matter Waves

All About Atoms

Conduction of Electricity in Solids

Nuclear Physics

Energy From the Nucleus

Quarks, Leptons, and the Big Bang

Filters

The quantity (B²/ $\mu$ _o)has units of: