Deck 9: Magnetism and Electromagnetic Induction

Question 1

An iron nail is attracted

A)more strongly to the north pole of a magnet.
B)more strongly to the south pole of a magnet.
C)equally to either pole of a magnet.
D)none of the above

Answer 1

C

Question 2

If you break a bar magnet in half you'll

A)destroy its magnetic properties.
B)have two magnets.
C)have four magnets.
D)none of the above

Answer 2

B

Question 3

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

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

Answer 3

A

Question 4

Every spinning electron is

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

Question 5

Surrounding every moving electron is

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

Question 6

Surrounding every stationary electron is

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

Question 7

A compass needle in a magnetic field experiences

A)a torque.
B)a net force.
C)both of these
D)none of the above

Question 8

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

Question 9

Compared with 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 10

A strong magnetic field easily penetrates

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

Question 11

Magnetism is due to the motion of electrons as they

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

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

An iron rod becomes magnetic when

A)opposite ions accumulate at each end.
B)its atoms are aligned.
C)the net spins of many internal electrons are aligned.
D)its electrons stop moving and point in the same direction.

Question 14

Unlike electric charges,magnetic poles cannot be

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

Question 15

Refrigerator magnets are typically

A)short range.
B)long range.
C)none of these

Question 16

Wood does not have magnetic properties because it contains no

A)iron or other metals.
B)magnetic domains.
C)moving electrons.
D)none of the above

Question 17

The ultimate source of all magnetism is

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

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

Every magnet contains at least

A)one pole.
B)two poles.
C)four poles.

Question 20

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

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

Question 21

The minimum or no magnetic force on a moving electron occurs for motion

A)parallel to the magnetic field.
B)perpendicular to the magnetic field.
C)at non-right angles to the magnetic field direction.

Question 22

A bar magnet that holds a chain of nails illustrates

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

Question 23

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)either of these
D)neither of these

Question 24

The lift experienced by Maglev trains is due to magnetic

A)attraction.
B)repulsion.
C)dipoles.

Question 25

The magnetic field lines about a straight current-carrying wire are

A)circular.
B)radial.
C)elliptical.
D)spiral.

Question 26

The magnetic field lines generated by a bar magnet

A)are external only.
B)are both external and internal to the magnet.
C)follow an inverse-square law.
D)none of the above

Question 27

A common electromagnet consists of a

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

Question 28

A superconducting electromagnet makes use of

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

Question 29

Moving electric charges will interact with

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

Question 30

Magnetic field lines about a current-carrying wire

A)extend radially from the wire.
B)circle the wire in closed loops.
C)both of these
D)none of the above

Question 31

When current reverses direction in a wire,the surrounding magnetic field

A)also reverses direction.
B)becomes momentarily stronger.
C)contracts.
D)expands.

Question 32

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

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

Question 33

When a bar magnet is broken in half,the strength of the four new poles relative to pole strength before breaking is

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

Question 34

When a current-carrying wire is bent into a loop,its magnetic field inside the loop

A)weakens.
B)becomes concentrated.
C)cancels.
D)none of the above

Question 35

Into which stable force field can a proton be placed at rest without being accelerated?

A)magnetic field
B)electric field
C)both of these
D)none of the above

Question 36

As the number of loops in a current-carrying wire coil is increased,the magnetic field becomes

A)more spread out.
B)more stable.
C)stronger.
D)weaker.
E)none of the above

Question 37

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 38

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 non-right angles to the magnetic field direction.
E)none of the above

Question 39

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)an iron core is inserted.
D)all of the above
E)none of the above

Question 40

Superconducting electromagnets

A)account for cases of magnetic levitation.
B)are characterized by easy penetration of external magnetic fields.
C)both of these
D)none of the above

Question 41

Earth's magnetic field affects cosmic rays by

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

Question 42

In which of these locations is cosmic ray intensity greatest?

A)Mexico City
B)Toronto
C)Singapore
D)all about the same

Question 43

Near our planet Earth are

A)cosmic rays.
B)magnetic fields.
C)both of these
D)none of the above

Question 44

Which of these singly ionized atoms of the same speed will curve most in a magnetic field?

A)helium
B)iron
C)uranium
D)all the same

Question 45

Since magnetic force on a moving electron is always perpendicular to its direction of motion,magnetic force is unable to change an electron's

A)speed.
B)direction.
C)speed and direction.
D)none of the above

Question 46

No net force acts on a loop of wire in a magnetic field when

A)no current is in the loop.
B)no magnetic field lines pass through the loop.
C)both of these
D)neither of these

Question 47

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

A)the poles.
B)mid-latitudes.
C)the equator.
D)no particular locations.

Question 48

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 of these
D)none of the above

Question 49

An electron beam directed through a magnetic field

A)may be deflected.
B)may experience a force.
C)both of these
D)neither of these

Question 50

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

A)electric field
B)magnetic field
C)both of these
D)none of the above

Question 51

Faraday's law 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 52

The discovery of electromagnetic induction is credited to

A)Joseph Henry in America.
B)Michael Faraday in England.
C)both of these
D)none of the above

Question 53

A galvanometer calibrated to read current is

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

Question 54

When an electron passes through the magnetic field of a horseshoe magnet,the electron's

A)speed is increased.
B)direction of motion is changed.
C)both of these
D)none of the above

Question 55

A galvanometer calibrated to read potential difference is

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

Question 56

A galvanometer is a useful device in electric

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

Question 57

If a magnet produces a force on a current-carrying wire,the wire

A)produces a force on the magnet.
B)may or may not produce a force on the magnet.
C)neither of these

Question 58

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

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

Question 59

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 of these
D)none of the above

Question 60

A galvanometer measures

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

Question 61

Fred swings a sheet of copper in pendulum fashion between the poles of a strong magnet.The sheet slows in entering the magnetic field because the field

A)induces swirling currents in the copper and accompanying magnetic fields that resist motion.
B)experiences both air and magnetic friction.
C)is repelled by free electrons in the copper.
D)none of the above

Question 62

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

A)voltage.
B)current.
C)both of these
D)none of the above

Question 63

Compared with a motor,a generator is

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

Question 64

Electromagnetic induction is employed in

A)credit card readers.
B)computers.
C)mobile phones.
D)all of the above
E)none of the above

Question 65

If you drop a bar magnet in a vertical copper pipe it will fall slowly because

A)of air resistance.
B)it induces a magnetic field in the pipe that resists motion of the magnet.
C)the copper is a good conductor of both electricity and magnetism.
D)of electron repulsion.

Question 66

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.

Question 67

When a bar magnet is thrust into a coil of wire,the coil

A)attracts the magnet as it enters.
B)repels the magnet as it enters.
C)both of these
D)none of the above

Question 68

Changing the magnetic field intensity in a copper coil induces

A)current.
B)voltage.
C)both of these
D)none of the above

Question 69

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 70

When a bar magnet is thrust at the same speed into a coil having 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 71

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 72

The current produced by a common generator is

A)dc.
B)ac.
C)neither of these

Question 73

The amount of current produced by electromagnetic induction depends on the

A)amount of induced voltage.
B)resistance of the circuit to which it is connected.
C)both of these
D)none of the above

Question 74

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 75

The frequency with which a magnet plunges into and out of a wire coil equals the frequency of the induced

A)voltage.
B)current.
C)both of these
D)none of the above

Question 76

Alternating current is normally produced by a

A)battery.
B)generator.
C)both of these
D)none of the above

Question 77

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

A)a greater number of loops in the coil.
B)faster thrusting motion.
C)a stronger bar magnet.
D)all of the above

Question 78

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

A)electric field intensity.
B)magnetic field intensity.
C)voltage.
D)the coil's polarity.
E)none of the above

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

A copper ring can be made to levitate about the extended bar of an electromagnet because the magnetic field induced in the ring

A)remains strong and steady.
B)opposes the field producing it.
C)is attracted to the top end of the bar.
D)none of the above