Question 1

An emf of 0.52 V is induced in a 0.62-H inductor.What is the rate of change of current through the inductor?

Accepted Answer

A)  0.84 A/s 
B)  1.2 A/s 
C)  0.32 A/s 
D)  1.14 A/s 
E)  ​0.62 A/s 
A)  0.84 A/s 
B)  1.2 A/s 
C)  0.32 A/s 
D)  1.14 A/s 
E)  ​0.62 A/s

Question 2

By what factor is the self-inductance of an air solenoid changed if its length and number of coil turns both multiplied by eight?

Accepted Answer

A)  1/8 
B)  8 
C)  1 
D)  64 
E)  ​1/64 
A)  1/8 
B)  8 
C)  1 
D)  64 
E)  ​1/64

Question 3

A double loop of wire (making 2 turns)is in the x-y plane centered at the origin.A uniform magnetic field is increasing at a constant rate in the positive z-direction.Viewed from the positive z-axis,in which direction is the induced magnetic field in the loop?

Accepted Answer

A)  in the positive z-direction 
B)  in the negative z-direction 
C)  There is no induced field because of the double loop. 
D)  There is no induced field because the rate of change of the magnetic field is constant. 
A)  in the positive z-direction 
B)  in the negative z-direction 
C)  There is no induced field because of the double loop. 
D)  There is no induced field because the rate of change of the magnetic field is constant.

Question 4

According to Lenz's law the direction of an induced current in a conductor will be that which tends to produce which of the following effects?

Accepted Answer

A)  enhance the effect which produces it 
B)  produce a greater heating effect 
C)  produce the greatest voltage 
D)  oppose the effect which produces it 
A)  enhance the effect which produces it 
B)  produce a greater heating effect 
C)  produce the greatest voltage 
D)  oppose the effect which produces it

Question 5

Three loops of wire,one circular,one rectangular,and one square,are made from identical lengths of wire.If the loops are in the same increasing magnetic field perpendicular to the plane of the coils,which loop has the greatest induced emf?

Accepted Answer

A)  the circular one 
B)  the rectangular one 
C)  the square one 
D)  All three would have the same emf induced. 
A)  the circular one 
B)  the rectangular one 
C)  the square one 
D)  All three would have the same emf induced.

Question 6

A uniform 1.1-T magnetic field passes perpendicularly through the plane of a wire loop 0.40 m2 in area.What flux passes through the loop?

Accepted Answer

A)  4.4 T⋅m2 
B)  0.44 T⋅m2 
C)  3 T⋅m2 
D)  0.18 T⋅m2 
E)  ​1.3 T·m2 
A)  4.4 T⋅m2 
B)  0.44 T⋅m2 
C)  3 T⋅m2 
D)  0.18 T⋅m2 
E)  ​1.3 T·m2

Question 7

In a circuit made up of inductor L,resistance R,ammeter,battery and switch in series,the current is greatest at which of the following times,as measured after the switch is closed?

Accepted Answer

A)  zero 
B)  one time constant 
C)  at a time t = L/R 
D)  ten time constants 
A)  zero 
B)  one time constant 
C)  at a time t = L/R 
D)  ten time constants

Question 8

A loop of area 0.120 m2 is in a uniform 0.0500-T magnetic field.If the flux through the loop is 4.09 × 10-3 T·m2,what angle does the normal to the plane of the loop make with the direction of the magnetic field?

Accepted Answer

A)  47.0° 
B)  83.5° 
C)  43.0° 
D)  79.1º 
E)  ​This is not possible. 
A)  47.0° 
B)  83.5° 
C)  43.0° 
D)  79.1º 
E)  ​This is not possible.

Question 9

A straight wire lies along the y-axis initially carrying a current of 10 A in the positive y-direction.The current decreases and reverses to 10 A in the negative y-direction,the change in current happening at a uniform rate.In the 1st quadrant a square conducting coil has 2 sides parallel to the y-axis and the other 2 sides parallel to the x-axis.The side of the coil nearest and parallel to the straight wire is at a distance equal to the length of one of the sides of the square.As the current is going from 10 A in one direction to 10 A in the other,in which direction is the induced current in this side of the square coil nearest to the straight wire?

Accepted Answer

A)  It is in the positive y-direction. 
B)  It is in the negative y-direction. 
C)  At first it is in the positive y-direction,but after the current passes through zero,it is in the negative y-direction. 
D)  At first it is in the negative y-direction but after the current passes through zero,it is in the positive y-direction. 
A)  It is in the positive y-direction. 
B)  It is in the negative y-direction. 
C)  At first it is in the positive y-direction,but after the current passes through zero,it is in the negative y-direction. 
D)  At first it is in the negative y-direction but after the current passes through zero,it is in the positive y-direction.

Question 10

The unit of inductance,the henry,is equivalent to:

Accepted Answer

A)  V·s/A. 
B)  V/m. 
C)  J/C. 
D)  none of the units given. 
A)  V·s/A. 
B)  V/m. 
C)  J/C. 
D)  none of the units given.

Question 11

The self-inductance of a solenoid increases under which of the following conditions?

Accepted Answer

A)  Only the solenoid length is increased. 
B)  Only the cross sectional area is decreased. 
C)  Only the number of coils per unit length is decreased. 
D)  Only the number of coils is increased. 
A)  Only the solenoid length is increased. 
B)  Only the cross sectional area is decreased. 
C)  Only the number of coils per unit length is decreased. 
D)  Only the number of coils is increased.

Question 12

The units T·m2/s are equivalent to:

Accepted Answer

A)  W. 
B)  V. 
C)  N/m. 
D)  webers. 
A)  W. 
B)  V. 
C)  N/m. 
D)  webers.

Question 13

A rectangular loop (area = 0.30 m2)turns in a uniform magnetic field with B = 0.50 T.At an instant when the angle between the magnetic field and the normal to the plane of the loop is π/2 rads and increasing at the rate of 0.52 rad/s,what is the magnitude of the emf induced in the loop?

Accepted Answer

A)  150 mV 
B)  zero 
C)  78 mV 
D)  290 mV 
E)  ​41 mV 
A)  150 mV 
B)  zero 
C)  78 mV 
D)  290 mV 
E)  ​41 mV

Question 14

The operation of an electric motor depends on which of the following effects?

Accepted Answer

A)  the Doppler effect 
B)  the photoelectric effect 
C)  the force acting on a current-carrying wire in a magnetic field 
D)  current from the motion of a wire in a magnetic field 
A)  the Doppler effect 
B)  the photoelectric effect 
C)  the force acting on a current-carrying wire in a magnetic field 
D)  current from the motion of a wire in a magnetic field

Question 15

A series circuit contains a 14-V battery,a 3.3-Ω resistor,and a 3.8-mH inductor.If the switch to the battery is closed at t = 0,find the time required for the current in the circuit to reach 63% of its final value.

Accepted Answer

A)  1.2 ms 
B)  13 ms 
C)  0.87 ms 
D)  16 ms 
E)  ​0.08 ms 
A)  1.2 ms 
B)  13 ms 
C)  0.87 ms 
D)  16 ms 
E)  ​0.08 ms

Question 16

A flat coil of wire consisting of 15 turns,each with an area of 90 cm2,is positioned perpendicularly to a uniform magnetic field that increases its magnitude at a constant rate from 3.5 T to 5.9 T in 2.0 s.If the coil has a total resistance of 0.20 Ω,what is the magnitude of the induced current?

Accepted Answer

A)  1990 mA 
B)  81 mA 
C)  810 mA 
D)  130 mA 
E)  ​320 mA 
A)  1990 mA 
B)  81 mA 
C)  810 mA 
D)  130 mA 
E)  ​320 mA

Question 17

The function of the electric motor is which one of the following conversion processes?

Accepted Answer

A)  mechanical energy to electrical 
B)  electrical energy to mechanical 
C)  low voltage to high or vice versa 
D)  alternating current to direct 
A)  mechanical energy to electrical 
B)  electrical energy to mechanical 
C)  low voltage to high or vice versa 
D)  alternating current to direct

Question 18

What is the self-inductance in a coil that experiences a 4.7-V induced emf when the current is changing at a rate of 200 A/s?

Accepted Answer

A)  43 mH 
B)  110 mH 
C)  200 mH 
D)  24 mH 
E)  ​94 mH 
A)  43 mH 
B)  110 mH 
C)  200 mH 
D)  24 mH 
E)  ​94 mH

Question 19

A 500-turn circular coil with an area of 0.0650 m2 is mounted on a rotating frame,which turns at a rate of 18.0 rad/s in the presence of a 0.0350-T uniform magnetic field that is perpendicular to the axis of rotation.What is the instantaneous emf in the coil at the moment that the normal to its plane is perpendicular to the field?

Accepted Answer

A)  20.5 V 
B)  zero 
C)  0.063 V 
D)  369 V 
E)  ​1.14 V 
A)  20.5 V 
B)  zero 
C)  0.063 V 
D)  369 V 
E)  ​1.14 V

Question 20

If a bar magnet is falling through a loop of wire,the induced current in the loop of wire sets up a field which exerts a force on the magnet.This force between the magnet and the loop will be attractive when:

Accepted Answer

A)  the magnet enters the loop. 
B)  the magnet is halfway through. 
C)  the magnet is leaving the loop. 
D)  never. 
A)  the magnet enters the loop. 
B)  the magnet is halfway through. 
C)  the magnet is leaving the loop. 
D)  never.

Exam 20: Induced Voltages and Inductance

An emf of 0.52 V is induced in a 0.62-H inductor.What is the rate of change of current through the inductor?

By what factor is the self-inductance of an air solenoid changed if its length and number of coil turns both multiplied by eight?

A double loop of wire (making 2 turns)is in the x-y plane centered at the origin.A uniform magnetic field is increasing at a constant rate in the positive z-direction.Viewed from the positive z-axis,in which direction is the induced magnetic field in the loop?

According to Lenz's law the direction of an induced current in a conductor will be that which tends to produce which of the following effects?

Three loops of wire,one circular,one rectangular,and one square,are made from identical lengths of wire.If the loops are in the same increasing magnetic field perpendicular to the plane of the coils,which loop has the greatest induced emf?

A uniform 1.1-T magnetic field passes perpendicularly through the plane of a wire loop 0.40 m2 in area.What flux passes through the loop?

In a circuit made up of inductor L,resistance R,ammeter,battery and switch in series,the current is greatest at which of the following times,as measured after the switch is closed?

A loop of area 0.120 m2 is in a uniform 0.0500-T magnetic field.If the flux through the loop is 4.09 × 10-3 T·m2,what angle does the normal to the plane of the loop make with the direction of the magnetic field?

The unit of inductance,the henry,is equivalent to:

The self-inductance of a solenoid increases under which of the following conditions?

The units T·m2/s are equivalent to:

A rectangular loop (area = 0.30 m2)turns in a uniform magnetic field with B = 0.50 T.At an instant when the angle between the magnetic field and the normal to the plane of the loop is π/2 rads and increasing at the rate of 0.52 rad/s,what is the magnitude of the emf induced in the loop?

The operation of an electric motor depends on which of the following effects?

A series circuit contains a 14-V battery,a 3.3-Ω resistor,and a 3.8-mH inductor.If the switch to the battery is closed at t = 0,find the time required for the current in the circuit to reach 63% of its final value.

A flat coil of wire consisting of 15 turns,each with an area of 90 cm2,is positioned perpendicularly to a uniform magnetic field that increases its magnitude at a constant rate from 3.5 T to 5.9 T in 2.0 s.If the coil has a total resistance of 0.20 Ω,what is the magnitude of the induced current?

The function of the electric motor is which one of the following conversion processes?

What is the self-inductance in a coil that experiences a 4.7-V induced emf when the current is changing at a rate of 200 A/s?

If a bar magnet is falling through a loop of wire,the induced current in the loop of wire sets up a field which exerts a force on the magnet.This force between the magnet and the loop will be attractive when:

Introduction

Introduction: Part A

Motion in One Dimension

Motion in One Dimension: Part A

Vectors and Two-Dimensional Motion

Vectors and Two-Dimensional Motion: Part A

The Laws of Motion

The Laws of Motion: Part A

Energy

Energy: Part A

Momentum and Collisions

Momentum and Collisions: Part A

Rotational Motion and the Law of Gravity

Rotational Motion and the Law of Gravity: Part A

Rotational Equilibrium and Rotational Dynamics

Rotational Equilibrium and Rotational Dynamics: Part A

Solids and Fluids

Solids and Fluids: Part A

Thermal Physics

Thermal Physics: Part A

Energy in Thermal Processes Heat and Internal Energy

Energy in Thermal Processes Heat and Internal Energy: Part A

The Laws of Thermodynamics Work in Thermodynamic Processes

The Laws of Thermodynamics Work in Thermodynamic Processes: Part A

Vibrations and Waves

Vibrations and Waves: Part A

Sound

Sound: Part A

Electric Forces and Electric Fields

Electric Forces and Electric Fields: Part A

Electrical Energy and Capacitance

Electrical Energy and Capacitance: Part A

Current and Resistance Electric Current

Current and Resistance Electric Current: Part A

Direct-Current Circuits Sources of EMF

Direct-Current Circuits Sources of EMF: Part A

Magnetism Magnets

Magnetism Magnets: Part A

Induced Voltages and Inductance: Part A

Alternating-Current Circuits and Electromagnetic Waves

Alternating-Current Circuits and Electromagnetic Waves: Part A

Reflection and Refraction of Light

Reflection and Refraction of Light: Part A

Mirrors and Lenses

Mirrors and Lenses: Part A

Wave Optics

Wave Optics: Part A

Optical Instruments

Optical Instruments: Part A

Relativity

Relativity: Part A

Quantum Physics Blackbody Radiation and Plancks Hypothesis

Quantum Physics Blackbody Radiation and Plancks Hypothesis: Part A

Atomic Physics

Atomic Physics: Part A

Nuclear Physics

Nuclear Physics: Part A

Nuclear Energy and Elementary Particles

Nuclear Energy and Elementary Particles: Part A

Particle Collisions, Mediating Photons, and Quark Structures: Exploring the Fundamentals of Physics

Filters

A uniform 1.1-T magnetic field passes perpendicularly through the plane of a wire loop 0.40 m² in area.What flux passes through the loop?

A loop of area 0.120 m² is in a uniform 0.0500-T magnetic field.If the flux through the loop is 4.09 × 10^-3 T·m²,what angle does the normal to the plane of the loop make with the direction of the magnetic field?

The units T·m²/s are equivalent to:

A rectangular loop (area = 0.30 m²)turns in a uniform magnetic field with B = 0.50 T.At an instant when the angle between the magnetic field and the normal to the plane of the loop is π/2 rads and increasing at the rate of 0.52 rad/s,what is the magnitude of the emf induced in the loop?

A flat coil of wire consisting of 15 turns,each with an area of 90 cm²,is positioned perpendicularly to a uniform magnetic field that increases its magnitude at a constant rate from 3.5 T to 5.9 T in 2.0 s.If the coil has a total resistance of 0.20 Ω,what is the magnitude of the induced current?