# chapter 24 physics 101

Flashcard maker : Jason Westley
1) Magnetic compasses reportedly were first used for navigation by
A) Aristotle.
B) Australian aborigines.
C) Chinese sailors.
D) none of the above
c
2) 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
d
3) 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
c
4) 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
c
5) Like kinds of magnetic poles repel while unlike kinds of magnetic poles
A) attract.
B) repel also.
C) may attract or repel.
a
7) Whereas electric charges can be isolated, magnetic poles
A) can also.
B) cannot.
C) gather in clusters.
D) none of the above
b
8) Refrigerator magnets are typically
A) short range.
B) long range.
C) none of these
a
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
b
10) Surrounding every magnet is
A) a magnetic field.
B) an electric field.
C) both of these
D) neither of these
a
11) Surrounding every stationary electron is
A) a magnetic field.
B) an electric field.
C) both of these
D) neither of these
b
12) Surrounding every moving electron is
A) a magnetic field.
B) an electric field.
C) both of these
D) neither of these
c
13) Magnetic fields are produced by
A) a tiny fraction of moving electrical charges.
B) most moving electrical charges.
C) all moving electrical charges.
c
14) 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
c
15) The conventional direction of magnetic field lines outside a magnet are from
A) north to south.
B) south to north.
C) either way
a
16) Magnetic field strength about a magnet is strongest where magnetic field lines are
A) closer together.
B) straightest.
C) most curved.
a
18) The magnetic fields of a pair of nearby magnets can
C) add or subtract by vector rules.
c
19) 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
a
22) In the atoms of most materials the fields of individual electrons
A) cancel one another.
B) partly align.
C) completely align.
a
25) 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
c
27) The shape of a magnetic field surrounding a current-carrying conductor is
A) consistent with the inverse-square law.
C) circular.
D) all of these
E) neither of these
c
28) 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
b
29) When current reverses direction in a wire, the surrounding magnetic field
A) also reverses direction.
B) becomes momentarily stronger.
C) contracts.
D) expands.
a
30) 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
b
31) 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.
b
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
b
33) 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
a
35) A current-carrying coil of wire is
A) a superconductor.
B) a superconducting magnet.
C) an electromagnet.
D) a magplane in the making.
c
39) 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.
b
40) 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.
b
44) 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
b
45) 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
b
46) 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
b
47) 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
c
48) 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
c
49) 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
c
52) A galvanometer can be calibrated to measure
A) electric current.
B) electric voltage.
C) both of these
D) none of these
c
53) 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
c
55) Which force field can increase a moving electron’s speed?
A) electric field
B) magnetic field
C) both of these
D) neither of these
a
56) Which force field can accelerate an electron?
A) electric field
B) magnetic field
C) both of these
D) neither of these
c
57) 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.
c
58) Solar winds headed in Earth’s direction are deviated mainly by
A) the upper atmosphere.
B) the troposphere.
C) Earth’s magnetic field.
c
60) The intensity of cosmic rays bombarding the Earth’s surface is most at the
A) poles.
B) mid-latitudes.
C) equator.
a
61) 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
d
62) Cosmic rays penetrate your body when
B) outdoors.
C) in mountainous regions.
D) all of the above
E) none of the above
d
63) 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.
c
64) 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
c