Deck 9: Magnetism and Electromagnetic Induction

Question 1

Every spinning electron is

A)electrically charged.
B)is a tiny magnet.
C)both
D)none of the above

Answer 1

C

Question 2

An iron nail is more strongly attracted to the

A)north pole of a magnet.
B)south pole of a magnet.
C)north or south pole-no difference.

Answer 2

C

Question 3

Magnet A has twice the magnetic field strength of magnet B and pulls on magnet B with a force of 100 N. The amount of force that magnet A exerts on magnet B is

A)at or about 50 N.
B)exactly 100 N.
C)more than 100 N.
D)not enough information

Answer 3

B

Question 4

A magnetic field easily penetrates

A)human flesh.
B)plastic coatings.
C)both
D)none of the above

Question 5

Unlike electric charges, magnetic poles cannot be

A)located.
B)isolated.
C)destroyed.

Question 6

Break a bar magnet in half and each half is

A)a complete magnet.
B)a stronger magnet.
C)no longer magnetized.

Question 7

Every magnet contains at least

A)one pole.
B)two poles.
C)two or more poles.

Question 8

Surrounding every moving electron is

A)a magnetic field.
B)an electric field.
C)both
D)neither

Question 9

Like kinds of magnetic poles repel while unlike kinds of magnetic poles

A)attract.
B)repel also.
C)may attract or repel.

Question 10

What is the cause of a magnetic field about a permanent magnet, and about a current-carrying wire?

Question 11

A bar magnet that holds a chain of nails illustrates

A)magnetic field displacement.
B)magnetic induction.
C)electromagnetic induction.

Question 12

A magnet will become weaker if it is

A)dropped on a hard surface.
B)held in a hot flame.
C)either
D)neither

Question 13

The rule for the interaction of magnetic poles is similar to the rule for electric

A)circuits.
B)polarization.
C)charges.

Question 14

An iron rod becomes magnetic when

A)positive ions accumulate at one end and negative ions at the other end.
B)its atoms are aligned with positive charges on one side and negative charges on the other side.
C)the net spins of its electrons are in the same direction.
D)electron motion stops.
E)none of the above

Question 15

The source of all magnetism is

A)tiny bits of iron.
B)tiny domains of aligned atoms.
C)ferromagnetic materials.
D)moving electric charge.

Question 16

Several paper clips dangle from the north pole of a magnet. The induced pole in the bottom of the lowermost paper clip is a

A)north pole.
B)south pole.
C)north or south pole-no difference.

Question 17

Refrigerator magnets

A)have short range.
B)are without magnetic poles.
C)both

Question 18

Magnetic domains normally occur in

A)iron.
B)copper.
C)silver.
D)all of the above
E)none of the above

Question 19

Compared to the huge force that attracts an iron tack to a strong magnet, the force that the tack exerts on the magnet is

A)relatively small.
B)equally huge.
C)not enough information

Question 20

Magnetism is due to the motion of electrons as they

A)move around the nucleus.
B)spin on their axes.
C)both
D)neither

Question 21

No magnetic force acts on a current carrying wire when it

A)carries a very small current.
B)is perpendicular to the magnetic field.
C)either or both
D)none of the above

Question 22

The intensity of cosmic rays bombarding the Earth's surface is largest at the

A)poles.
B)mid-latitudes.
C)equator.

Question 23

An electromagnet consists of a

A)bar magnet that carries an electric current.
B)coil of wire.
C)current-carrying coil with a piece of iron inside.

Question 24

Superconducting electromagnets

A)exist now.
B)may be possible in the near future.
C)are not possible.
D)are science fiction.

Question 25

Magnetic field lines about a current-carrying wire

A)extend radially from the wire.
B)circle the wire in closed loops.
C)both
D)neither

Question 26

Surrounding our planet Earth are

A)cosmic rays.
B)magnetic fields.
C)both

Question 27

A magnetic field exists in a current-carrying coil of wire

A)if it contains a piece of iron.
B)with or without a contained piece of iron.
C)only if the current changes.

Question 28

The magnetic field strength inside a current-carrying coil will be greater if the coil encloses a

A)vacuum.
B)wooden rod.
C)glass rod.
D)iron rod.
E)none of the above

Question 29

When the current in a wire is reversed, the direction of the surrounding magnetic field

A)also reverses.
B)remains steady.
C)collapses.

Question 30

The minimum magnetic force on a moving electron occurs for motion

A)parallel to the magnetic field.
B)perpendicular to the magnetic field.
C)at an angle other than 90° to the magnetic field.

Question 31

A superconducting electromagnet makes use of

A)low-resistance coils of wire.
B)super-high temperatures.
C)high-speed electrons.
D)close packing of high-density magnetic domains.

Question 32

Maximum magnetic force occurs when electrons move

A)in the same direction as the magnetic field.
B)opposite to the magnetic field direction.
C)perpendicular to the magnetic field direction.
D)at an angle other than 90° to the magnetic field direction.
E)none of the above

Question 33

Moving electric charges will interact with

A)an electric field.
B)a magnetic field.
C)both
D)none of the above

Question 34

Earth's magnetic field affects cosmic rays by

A)deflecting them.
B)slowing their speeds.
C)destroying them.
D)absorbing them.

Question 35

The magnetic field lines about a current-carrying wire form

A)circles.
B)radial lines.
C)eddy currents.
D)spirals.

Question 36

When a current-carrying wire in a magnetic field experiences no force it is likely

A)upside down relative to the field.
B)overly insulated.
C)parallel to the field lines.
D)all of the above

Question 37

The magnetic field inside a current-carrying coil increases when

A)current is increased.
B)the number of loops of wire in the coil increases.
C)both.
D)none of the above

Question 38

A magnetic force acts most strongly on a current carrying wire when it

A)carries a very large current.
B)is perpendicular to the magnetic field.
C)either or both
D)none of the above

Question 39

Distinguish between a common bar magnet and an electromagnet.

Question 40

When a bar magnet is broken in half, the magnetic strength of each piece is

A)less than half.
B)about half.
C)the same.
D)somewhat increased.

Question 41

A galvanometer calibrated to read potential difference is

A)an ammeter.
B)a voltmeter.
C)an ohm meter.
D)none of the above

Question 42

When a magnet is thrust into a coil of wire, a greater voltage is induced

A)with a greater number of loops in the coil.
B)with faster thrusting motion.
C)both
D)neither

Question 43

Voltage can be induced in a wire by

A)moving the wire near a magnet.
B)moving a magnet near the wire.
C)changing the current in a nearby wire.
D)all of the above
E)none of the above

Question 44

A device that transforms electrical energy to mechanical energy is a

A)generator.
B)motor.
C)transformer.
D)magnet.
E)none of the above

Question 45

Changing the magnetic field intensity in a closed loop of wires induces

A)current.
B)voltage.
C)both
D)neither

Question 46

Thrust a magnet into a coil of wire and you'll induce

A)voltage.
B)current.
C)both
D)neither

Question 47

A galvanometer measures

A)magnetic fields.
B)electric current.
C)electric voltage.
D)none of the above

Question 48

Since magnetic force is always perpendicular to moving charges, magnetic force can only change an electron's

A)speed.
B)direction.
C)speed and direction.

Question 49

An electric motor and electric generator are

A)very similar devices.
B)entirely different devices.
C)none of the above

Question 50

A galvanometer is a useful device in electric

A)electromagnets.
B)transformers.
C)generators and motors.
D)meters.
E)none of the above

Question 51

When a change of magnetic field occurs in a closed loop of wire,

A)a voltage is induced in the wire.
B)current is made to flow in the loop of wire.
C)electromagnetic induction occurs.
D)all of the above
E)none of the above

Question 52

Which force field can both accelerate an electron and change its speed?

A)electric field.
B)magnetic field.
C)both
D)neither

Question 53

What happens to a current-carrying wire in a magnetic field? How does orientation of the wire make a difference?

Question 54

An electric motor and electric generator differ in

A)the roles of input and output.
B)basic construction.
C)size.
D)quality.

Question 55

Electromagnetic induction was discovered by

A)Joseph Henry.
B)Michael Faraday.
C)both
D)neither

Question 56

A device that transforms mechanical energy to electrical energy is a

A)generator.
B)motor.
C)transformer.
D)magnet.
E)none of the above

Question 57

Which force field can increase a moving electron's speed?

A)electric field
B)magnetic field
C)both
D)neither

Question 58

Faraday's law is the law that describes

A)electromagnetic induction.
B)the connection between current, voltage, and resistance.
C)the attraction and repulsion of magnetic poles.
D)the force between magnetic poles.
E)all of the above

Question 59

Electromagnetic induction occurs in a coil when there is a change in

A)electric field intensity in the coil.
B)magnetic field intensity in the coil.
C)voltage in the coil.
D)the coil's polarity.
E)electromagnetic polarity.

Question 60

A galvanometer calibrated to read current is

A)an ammeter.
B)a voltmeter.
C)an ohm meter.
D)none of the above

Question 61

The main difference between a generator and a motor involves which terminal is

A)input.
B)output.
C)both

Question 62

Alternating current is normally produced by a

A)battery.
B)generator.
C)both
D)neither

Question 63

Electromagnetic induction is employed in

A)credit cards.
B)computers.
C)iPads.
D)all of the above
E)none of the above

Question 64

Voltage produced by a generator alternates because

A)it produces pulses of current.
B)the magnetic field that produces it alternates.
C)alternations in the mechanical energy input.
D)in effect it is an ac motor in reverse.
E)the current it produces alternates.

Question 65

Compared to a motor, a generator is

A)one and the same.
B)its opposite.
C)of an entirely different design.

Question 66

State Faraday's law of induction and explain what it means.

Question 67

A topic that most underlies electrical studies and all of physics is

A)Newton's laws of motion.
B)the conservation of momentum.
C)the conservation of energy.

Question 68

Which of these statements is true?

A)a battery produces dc and a generator produces ac
B)a battery produces ac and a generator produces dc
C)a battery and a generator produce dc
D)a battery and a generator produce ac

Question 69

When a magnet is thrust into a coil that has twice the number of loops, the induced voltage is

A)half.
B)the same, no different.
C)twice as much.
D)four times as much.
E)none of the above

Question 70

The sloshing of electrons inside a generator need

A)an outside source of energy.
B)a copper lattice.
C)positive ions.
D)none of the above

Question 71

An electric generator of itself

A)can produce enough energy to light cities.
B)cannot produce energy, but convert energy of other forms to electric energy.
C)neither

Question 72

The metal detectors that travelers walk through at airports operate via

A)Ohm's law.
B)Faraday's law.
C)Coulomb's law.
D)Newton's laws.
E)civil laws.

Question 73

The energy source for a generator may be

A)a waterfall.
B)steam from a turbine.
C)wind.
D)any of these
E)none of the above

Question 74

Disregarding the effects of friction, a cyclist will coast farther when a lamp powered by a wheel generator is

A)of low wattage.
B)of high wattage.
C)burned out.
D)none of the above

Question 75

A transformer requires

A)alternating voltage.
B)direct current.
C)both
D)neither

Question 76

Power is the rate at which

A)energy is transferred.
B)voltage can be changed.
C)current can be induced.

Question 77

The frequency with which a magnet plunges into and out of a magnetic field equals the frequency of the induced

A)voltage.
B)current.
C)both
D)neither

Question 78

How are electric motors and electric generators similar? Different?

Question 79

Metal detectors that locate metal beneath sand on a beach are activated by

A)electric fields.
B)magnetic fields.
C)electromagnetic induction.
D)alternating current.

Question 80

When a magnet is thrust into a coil of wire, the coil tends to

A)attract the magnet as it enters.
B)repel the magnet as it enters.
C)both
D)neither