Question 1

"GFI" stands for:

Accepted Answer

A)  grand flux indicator. 
B)  ground forcing indicator. 
C)  ground fault interrupter. 
D)  gauss-free invention. 
A)  grand flux indicator. 
B)  ground forcing indicator. 
C)  ground fault interrupter. 
D)  gauss-free invention.

Question 2

By what factor is the self-inductance of an air solenoid changed if only its cross-sectional area,A,multiplied by six?

Accepted Answer

A)  1/6 
B)  6 
C)  12 
D)  36 
E)  ​1/36 
A)  1/6 
B)  6 
C)  12 
D)  36 
E)  ​1/36

Question 3

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

Accepted Answer

A)  zero 
B)  one time constant 
C)  reciprocal of one time constant 
D)  ten time constants 
A)  zero 
B)  one time constant 
C)  reciprocal of one time constant 
D)  ten time constants

Question 4

How is the energy stored in a current-carrying inductor related to the current value,I?

Accepted Answer

A)  directly proportional to I 2 
B)  directly proportional to I 1/2 
C)  directly proportional to I 
D)  inversely proportional to I 
A)  directly proportional to I 2 
B)  directly proportional to I 1/2 
C)  directly proportional to I 
D)  inversely proportional to I

Question 5

How is the energy stored in a current-carrying inductor related to its self-inductance,L?

Accepted Answer

A)  directly proportional to L2 
B)  directly proportional to L1/2 
C)  directly proportional to L 
D)  inversely proportional to L 
A)  directly proportional to L2 
B)  directly proportional to L1/2 
C)  directly proportional to L 
D)  inversely proportional to L

Question 6

If the induced current in a wire loop were such that the flux it produces were in the same direction as the change in external flux causing the current,which of the following conservation laws would end up being violated?

Accepted Answer

A)  momentum 
B)  charge 
C)  energy 
D)  angular momentum 
A)  momentum 
B)  charge 
C)  energy 
D)  angular momentum

Question 7

A coil is rotated in a magnetic field generating an emf given by emf = NBAω sin θ,where θ = ωt.At which angle θ is the emf one sixth of its maximum value?

Accepted Answer

A)  0° 
B)  10° 
C)  1.6° 
D)  80° 
E)  ​30º 
A)  0° 
B)  10° 
C)  1.6° 
D)  80° 
E)  ​30º

Question 8

The magnet moving past an object will produce eddy currents in the object if the object:

Accepted Answer

A)  is magnetic material only. 
B)  is a conductor. 
C)  is an insulator. 
D)  is a liquid. 
A)  is magnetic material only. 
B)  is a conductor. 
C)  is an insulator. 
D)  is a liquid.

Question 9

What is the stored energy in a 0.30-mH coil carrying a current of 6.0 A?

Accepted Answer

A)  1.1E-2 J 
B)  5.4E-3 J 
C)  1.8E-3 J 
D)  2.2E-2 J 
E)  ​2.0E-2 J 
A)  1.1E-2 J 
B)  5.4E-3 J 
C)  1.8E-3 J 
D)  2.2E-2 J 
E)  ​2.0E-2 J

Question 10

The basic function of the electric generator is which 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 11

An RL series circuit has: 5.3-mH coil,2.2-Ω resistor,15-V battery,ammeter and switch.After the switch is closed for a long time,find the final value of the current.

Accepted Answer

A)  1300 A 
B)  6.8 A 
C)  0.8 mA 
D)  33 A 
E)  ​0.17 A 
A)  1300 A 
B)  6.8 A 
C)  0.8 mA 
D)  33 A 
E)  ​0.17 A

Question 12

A straight wire of length l is oriented east-west and is in a magnetic field B pointing north.The wire is moving downward at a constant speed v.If the resistance of the rod is R,what is the current through the rod?

Accepted Answer

A)  R/Blv 
B)  Blv/R 
C)  B2l2v2/R2 
D)  not given 
A)  R/Blv 
B)  Blv/R 
C)  B2l2v2/R2 
D)  not given

Question 13

The "back emf" of a motor refers to a source of voltage that:

Accepted Answer

A)  occurs when the motor runs backwards. 
B)  occurs when the motor is used as a generator. 
C)  is biggest when the current through the motor is biggest. 
D)  is biggest when the motor turns fastest. 
A)  occurs when the motor runs backwards. 
B)  occurs when the motor is used as a generator. 
C)  is biggest when the current through the motor is biggest. 
D)  is biggest when the motor turns fastest.

Question 14

A 38-turn square coil of area 0.100 m2 and a 152-turn circular coil are both placed perpendicular to the same changing magnetic field.The voltage induced in each of the coils is the same.What is the area of the circular coil?

Accepted Answer

A)  0.400 m2 
B)  0.0063 m2 
C)  0.025 m2 
D)  0.100 m2 
E)  ​1.600 m2 
A)  0.400 m2 
B)  0.0063 m2 
C)  0.025 m2 
D)  0.100 m2 
E)  ​1.600 m2

Question 15

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.As the south pole leaves the loop of wire,the induced current (as viewed from above)will be:

Accepted Answer

A)  clockwise. 
B)  counterclockwise. 
C)  zero. 
D)  along the length of the magnet. 
A)  clockwise. 
B)  counterclockwise. 
C)  zero. 
D)  along the length of the magnet.

Question 16

An airplane with a wingspan of 68.0 m flies parallel to the Earth's surface at a point where the downward component of the Earth's magnetic field is 0.380 × l0−4 T.If the induced potential between wingtips is 0.600 V,what is the plane's speed?

Accepted Answer

A)  33.5 m/s 
B)  15.5 m/s 
C)  232 m/s 
D)  15,800 m/s 
E)  ​88 m/s 
A)  33.5 m/s 
B)  15.5 m/s 
C)  232 m/s 
D)  15,800 m/s 
E)  ​88 m/s

Question 17

Two solenoids,wound from wire from the same spool,have the same length and cross-sectional area,but solenoid №1 has half the turns of solenoid №2.If these solenoids are each connected to a circuit,and the only non-negligible resistance is that of the solenoids,which solenoid gives the greater time constant and by what factor?

Accepted Answer

A)  №1 by a factor of 2 
B)  №2 by a factor of 2 
C)  №2 by a factor of 4 
D)  No answer above is completely correct. 
A)  №1 by a factor of 2 
B)  №2 by a factor of 2 
C)  №2 by a factor of 4 
D)  No answer above is completely correct.

Question 18

The magnetic field going through a stationary circular loop increases from zero to 5 T in a certain time t.The induced current in the loop will depend on the radius of the loop,r,the resistance of the loop,R,and the time,t.If two of these stay constant,the induced current can be directly proportional to:

Accepted Answer

A)  t. 
B)  r. 
C)  R. 
D)  none of these 
A)  t. 
B)  r. 
C)  R. 
D)  none of these

Question 19

An RL series circuit has the following components: 4.8-mH coil,1.6-Ω resistor,13-V battery,ammeter and switch.What is the time constant of this circuit?

Accepted Answer

A)  3.3E+2 s 
B)  3.0E-3 s 
C)  1.7E-3 s 
D)  5.9E-4 s 
E)  ​3.9E-2 s 
A)  3.3E+2 s 
B)  3.0E-3 s 
C)  1.7E-3 s 
D)  5.9E-4 s 
E)  ​3.9E-2 s

Question 20

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.The induced current will be greatest in magnitude when the magnet is located so that:

Accepted Answer

A)  the loop is near either the north or the south pole. 
B)  the loop is near the north pole only. 
C)  the loop is near the middle of the magnet. 
D)  with no acceleration,the induced current is zero. 
A)  the loop is near either the north or the south pole. 
B)  the loop is near the north pole only. 
C)  the loop is near the middle of the magnet. 
D)  with no acceleration,the induced current is zero.

Exam 20: Induced Voltages and Inductance

"GFI" stands for:

By what factor is the self-inductance of an air solenoid changed if only its cross-sectional area,A,multiplied by six?

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

How is the energy stored in a current-carrying inductor related to the current value,I?

How is the energy stored in a current-carrying inductor related to its self-inductance,L?

If the induced current in a wire loop were such that the flux it produces were in the same direction as the change in external flux causing the current,which of the following conservation laws would end up being violated?

A coil is rotated in a magnetic field generating an emf given by emf = NBAω sin θ,where θ = ωt.At which angle θ is the emf one sixth of its maximum value?

The magnet moving past an object will produce eddy currents in the object if the object:

What is the stored energy in a 0.30-mH coil carrying a current of 6.0 A?

The basic function of the electric generator is which of the following conversion processes?

An RL series circuit has: 5.3-mH coil,2.2-Ω resistor,15-V battery,ammeter and switch.After the switch is closed for a long time,find the final value of the current.

A straight wire of length l is oriented east-west and is in a magnetic field B pointing north.The wire is moving downward at a constant speed v.If the resistance of the rod is R,what is the current through the rod?

The "back emf" of a motor refers to a source of voltage that:

A 38-turn square coil of area 0.100 m2 and a 152-turn circular coil are both placed perpendicular to the same changing magnetic field.The voltage induced in each of the coils is the same.What is the area of the circular coil?

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.As the south pole leaves the loop of wire,the induced current (as viewed from above)will be:

An airplane with a wingspan of 68.0 m flies parallel to the Earth's surface at a point where the downward component of the Earth's magnetic field is 0.380 × l0−4 T.If the induced potential between wingtips is 0.600 V,what is the plane's speed?

An RL series circuit has the following components: 4.8-mH coil,1.6-Ω resistor,13-V battery,ammeter and switch.What is the time constant of this circuit?

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.The induced current will be greatest in magnitude when the magnet is located so that:

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 38-turn square coil of area 0.100 m² and a 152-turn circular coil are both placed perpendicular to the same changing magnetic field.The voltage induced in each of the coils is the same.What is the area of the circular coil?

An airplane with a wingspan of 68.0 m flies parallel to the Earth's surface at a point where the downward component of the Earth's magnetic field is 0.380 × l0−⁴ T.If the induced potential between wingtips is 0.600 V,what is the plane's speed?