Deck 24: Magnetism

Question 1

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

Answer 1

both of these

Question 2

Surrounding every magnet is

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

Answer 2

a magnetic field.

Question 3

Magnetic field strength about a magnet is strongest where magnetic field lines are

A)closer together.
B)straightest.
C)most curved.
D)more spread.

Answer 3

closer together.

Question 4

Magnetic compasses reportedly were first used for navigation by

A)Aristotle.
B)Australian aborigines.
C)Chinese sailors.
D)none of the above

Question 5

The source of all magnetism is

A)tiny pieces of iron.
B)tiny domains of aligned atoms.
C)ferromagnetic materials.
D)moving electric charge.
E)none of the above

Question 6

A compass needle in a magnetic field

A)experiences a torque.
B)experiences a pair of torques.
C)may experience a pair of torques.

Question 7

Surrounding every moving electron is

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

Question 8

The force that acts between a pair of magnetic poles depends on

A)magnetic pole strength.
B)separation distance.
C)both of these
D)neither of these

Question 9

If you break a bar magnet in half you'll

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

Question 10

Refrigerator magnets are typically

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

Question 11

The end of a compass needle that points to the south pole of a magnet is the

A)north pole.
B)south pole.
C)both of these

Question 12

In general, a common magnet has

A)one pole.
B)at least two poles.
C)only two poles.

Question 13

The magnetic fields of a pair of nearby magnets can

A)only add.
B)cannot add or subtract.
C)add or subtract by vector rules.

Question 14

The conventional direction of magnetic field lines outside a magnet are from

A)north to south.
B)south to north.
C)either way

Question 15

Magnetic fields are produced by

A)a tiny fraction of moving electrical charges.
B)most moving electrical charges.
C)all moving electrical charges.

Question 16

Whereas electric charges can be isolated, magnetic poles

A)can also.
B)cannot.
C)gather in clusters.
D)none of the above

Question 17

Surrounding every stationary electron is

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

Question 18

An iron rod becomes magnetic when

A)opposite ions accumulate at each end.
B)its atoms are aligned.
C)the net spins of many of its electrons are aligned.
D)its electrons stop moving and point in the same direction.
E)none of the above

Question 19

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

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

Question 20

The force that acts between a pair of electrically-charged particles depends on

A)magnitude of charge.
B)separation distance.
C)both of these
D)neither of these

Question 21

An iron nail is more strongly attracted to the

A)north pole of a magnet.
B)south pole of a magnet.
C)either of these
D)neither of these

Question 22

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)neither of these

Question 23

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 24

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 25

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)inversely proportional to their masses.

Question 26

As the number of loops in a current-carrying wire is increased, the

A)more spread out is the magnetic field.
B)stronger the enclosed magnetic field.
C)weaker the current.
D)greater the back emf.

Question 27

The shape of a magnetic field surrounding a current-carrying conductor is

A)consistent with the inverse-square law.
B)radial.
C)circular.
D)all of these
E)neither of these

Question 28

Magnet A has twice the magnetic field strength of Magnet B and at a certain distance 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)need more information

Question 29

The lift experienced by Maglev trains is due to magnetic

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

Question 30

A superconducting magnet uses

A)iron cores.
B)superconducting coils.
C)both of these
D)neither of these

Question 31

A current-carrying loop of wire experiences no tendency to rotate in a magnetic field when

A)field lines pass directly through the loop.
B)no field lines pass through the loop.
C)none of these

Question 32

A beam of electrons passing through a magnetic field experiences maximum deflection if the direction of the beam is

A)parallel to the field lines.
B)perpendicular to the field lines.
C)none of these

Question 33

In the atoms of most materials the fields of individual electrons

A)cancel one another.
B)partly align.
C)completely align.

Question 34

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

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

Question 35

A beam of electrons can pass through a magnetic field without being deflected if the direction of the beam is

A)parallel to the field lines.
B)perpendicular to the field lines.
C)none of these

Question 36

To weaken a bar magnet

A)drop it on a hard surface.
B)put it in hot flames.
C)whack it with a hammer.
D)all of the above
E)none of the above

Question 37

A current-carrying coil of wire is

A)a superconductor.
B)a superconducting magnet.
C)an electromagnet.
D)a magplane in the making.

Question 38

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 39

Magnetic domains normally occur in

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

Question 40

Place an iron rod inside a current-carrying coil of wire and you

A)increase the strength of the electromagnet.
B)have a superconducting magnet.
C)a magplane in the making.

Question 41

Over geologic history the Earth's magnetic field

A)has been relatively stable.
B)has increased in strength exponentially.
C)has reversed direction many times.
D)is unknown.

Question 42

If a compass is moved from the Northern Hemisphere to the Southern Hemisphere, its magnetic needle will change direction

A)randomly and rapidly
B)by 90 degrees.
C)by 180 degrees.
D)hardly at all.

Question 43

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

A)speed is increased.
B)direction is changed.
C)both of these
D)neither of these

Question 44

A current-carrying wire in a magnetic field

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

Question 45

A beam of singly-charged ions entering a magnetic field are swept into circular paths. The wider paths are those of

A)the lighter ions.
B)the heavier ions.
C)neither particularly.

Question 46

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 47

The force a magnetic field exerts on a current-carrying wire is maximum when the wire is oriented

A)parallel to the magnetic field.
B)perpendicular to the magnetic field.
C)either of these
D)neither of these

Question 48

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)none of these

Question 49

A galvanometer can be calibrated to measure

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

Question 50

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 51

A galvanometer indicates

A)electric charge.
B)a flow of electrons.
C)electric voltage.
D)magnetic field strength.

Question 52

Which force field can accelerate an electron?

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

Question 53

Into which stable force field can a proton be placed at rest without being acted upon by a force?

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

Question 54

The force exerted on an electron moving in a magnetic field is maximum when the electron moves

A)parallel to the magnetic field.
B)perpendicular to the magnetic field.
C)either of these
D)neither of these

Question 55

The direction of the force exerted on a moving charge in a magnetic field is

A)in the direction of the motion.
B)opposite its motion.
C)at right angles to the direction of the motion.

Question 56

Solar winds headed in Earth's direction are deviated mainly by

A)the upper atmosphere.
B)the troposphere.
C)Earth's magnetic field.
D)Earth's radiation belts.

Question 57

Although a magnet can change the direction of travel of an electron beam, it cannot change its

A)speed
B)kinetic energy.
C)both of these
D)neither of these

Question 58

The force on an electron moving in a magnetic field will be least when its direction is

A)the same as the magnetic field direction.
B)perpendicular to the magnetic field direction.
C)either of these
D)neither of these

Question 59

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

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

Question 60

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

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

Question 61

Pigeons navigate primarily by

A)a good memory.
B)a keen sense of smell.
C)magnetic sensors in their heads.
D)ultra-high-pitched sounds.
E)none of the above

Question 62

Earth's magnetic field is

A)something we've learned to live with.
B)useful to pigeons but not to humans.
C)protective to life on Earth.

Question 63

An aurora borealis high above the atmosphere is due to

A)disturbances in Earth's magnetic field.
B)fountains of high-speed charged particles.
C)trapping of charged particles by Earth's magnetic field.
D)all of the above

Question 64

Biomagnetism has been detected in

A)bacteria.
B)pigeons.
C)wasps.
D)humans.
E)all of the above

Question 65

Cosmic rays penetrate your body when

A)safely in your home.
B)outdoors.
C)in mountainous regions.
D)all of the above
E)none of the above