92 terms

3. Physics Practice Questions - Magnetism and Electromagnetic Induction

http://www.mwood.cc/pages/uploaded_files/Microsoft%20Word%20-%20magnetism%20test%20questions.pdf
STUDY
PLAY
d
1 . 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 these
c
2. Moving electric charges will interact with
a. an electric field. b. a magnetic field. c. both of these d. none of these
c
3. An iron rod becomes magnetic when.
a. positive ions accumulate at _me end and negative ions at the other end.
b. its atoms are aligned having plus charges on one side and negative charges on the other.
c. the net spins of its electrons are in the same direction.
d. its electrons stop moving and point in the same direction.
e. none of these.
a
4. Like kinds of magnetic poles repel while unlike kinds of magnetic poles
a. attract. b. repel also. c. may attract or repel.
a
5. 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 really.
c
6. 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 really.
c
7. Surrounding every moving electron is
a. a magnetic field.
b. an electric field.
c. both of these
d. none of these
c
8 . 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. none of these
a
9. Magnetic domains normally occur in
a. iron.
b. copper.
c. silver.
d. all of these
e. none of these
b
10. 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
c
11 . The force on an electron moving in a magnetic field will be the largest when its direction is
a. the same as the magnetic field direction.
b. exactly 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 these
a
12. The intensity of cosmic rays bombarding the earth's surface is largest at the
a. poles.
b. mid-latitudes.
c. equator.
b
13. The magnetic north pole of the earth is nearest
a. the Hudson Bay region of Canada. b. Australia. c. both of these
a
14. Which pole of a compass needle points to a south pole of a magnet?
a. north pole.
b. south pole.
c. both of these
a
15. An electric motor and electric generator are
a. very similar devices. b. entirely different devices.
b
16. 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. More information is needed.
b
17. 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. More information is needed.
d
18. If a compass is moved from the northern hemisphere to the southern hemisphere, its magnetic
needle will change direction
a. by 180°.
b. depending on where the measurement is taken.
c. by 90°.
d. hardly at all.
e. none of these
d
19. A likely cause for the existence of the earth's magnetic field is
a. moving charges in the liquid part of the earth's core.
b. great numbers of very slow moving charges in the earth.
c. convection currents in the liquid part of the earth's core.
d. all of these
e. none of these
a
20. Which force field can increase a moving electron's speed?
a. electric field
b. magnetic field
c. both of these
d. none of these
b
21 . Which force field can accelerate an electron, but never change its speed?
a. electric field.
b. magnetic field.
c. both of these
d. none of these
c
22. When a bar magnet is broken in two as shown, each piece is
a. as magnetic as the original magnet.
b. actually stronger than the original magnet.
c. half as strong as the original magnet.
0. no longer magnetic.
d
23. When there is a change in the magnetic field 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 these
e. none of these
c
24. Thrust a magnet into a coil of wire and the coil
a. becomes an electromagnet.
b. has a current in it.
c. both of these
d. neither of these
b
25. 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 of these
d. neither of these
b
26. 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.
d
27. 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 these
e. none of these
d
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. rod of iron.
e. none of these
c
29. If a magnet is pushed into a coil, voltage is induced across the coil. If the same magnet is pushed
into a coil with twice the number of loops,
a. one-half as much voltage is induced.
b. the same voltage is induced.
c. twice as much voltage is induced.
d. four times as much voltage is induced.
e. none of these
b
30. A device that transforms electrical energy to mechanical energy is a
a. generator.
b. motor.
c. transformer.
d. magnet.
e. none of these
b
31. Voltage produced by a generator alternates because
a. unlike a battery, it produces alternating current.
b. the changing magnetic field that produces it alternates.
c. alterations in the mechanical energy input.
d. in effect it is an ac motor in reverse.
e. the current it produces alternates.
a
32. A transformer actually transforms
a. voltage.
b. magnetic field lines.
c. generators into motors.
d. non-safe forms of energy to safe forms of energy.
e. all of these
c
33. Transformers use ac so there will be the required
a. transfer of energy from coil to coil.
b. voltage for transformation.
c. change in magnetic field for operation.
d. change in input current.
e. magnetic field intensities.
a
34. Disconnect a small-voltage battery from a coil of many loops of wire, and a large voltage is
produced by
a. the large collapse in the magnetic field.
b. latent energy in the battery.
c. the resistance of the battery to a change in polarity.
d. electrons already in the wire.
e. the electric field between the battery terminals.
b
35. Power is transmitted at high voltages because the corresponding current in the wires is
a. also high to deliver appreciable power to distant places.
b. low so that overheating of the wires is minimized.
c. both of these
d. neither of these
a
36. Electric power can be transmitted from one place to another without the need for connecting wires
in between. This statement is
a. true.
b. false.
c
37. Rapid changes of a magnetic field induces
a. a magnetic field of greater magnitude.
b. a magnetic field of the same magnitude.
c. an electric field.
b
38. The metal detectors that people 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.
d
39. A step-up transformer increases
a. power.
b. energy.
c. both of these
d. neither of these
c
40. Changing the magnetic field intensity in a closed loop of wires induces
a. current.
b. voltage.
c. both of these
d. neither of these
c
41 . Metal detectors, like the ones used at airports, are activated by
a. electric fields.
b. magnetic fields.
c. electromagnetic induction.
d. alternating current.
c
42. The principal advantage of ac power over dc power is that
a. less energy is dissipated during transmission.
b. ac voltage oscillates while dc voltage does not.
c. ac voltage can be transformed via conventional transformers.
d. ac circuits multiply power more easily.
e. ac circuits are safer.
a
43. Neon signs require about 12,000 V to operate. If the circuit uses a 120-V power source, the ratio of
primary to secondary turns on the transformer should be
a. 1:100.
b. 100:1.
c. neither of these
c
44. A step-up transformer has a ratio of 1 to 10. Neglecting slight losses, if 100 W of power go into the
primary coil, the power corning from the secondary coil is
a. 1 W.
b. 10 W.
c. 100 W.
d. 1000 W.
e. none of these
b
45. The voltage across the input terminals of a transformer is 110 V. The primary has 50 loops and the
secondary has 25 loops. The voltage the transformer puts out is
a. 25 V.
b. 55 V.
c. 110 V.
d. 220 V.
e. none of these
c
46. Four amps of current exist in the primary coil of a transformer. The voltage across the primary coil
is 110 V. What is the power output of the secondary coil?
a. 27.5 W
b. 110 W
c. 440 W
d. 880 W
e. not enough information to say
b
47. A certain transformer doubles input voltage. If the primary coil has 10 A of current, then the
current in the secondary coil is
a. 2 A.
b. 5 A.
c. 10 A.
d. 25 A.
e. none of these
c
48. 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 these
b
49. As a motor armature turns faster and faster, net current in the motor windings
a. increases.
b. decreases.
c. remains unchanged.
d
50. If the primary of a transformer were connected to a dc power source, the transformer would have a voltage output
a. at a higher efficiency than with an ac source.
b. the same.
c. that is also dc.
d. only while being connected or disconnected.
e. none of these
c
51. What does the term magnetism come from?
a. the interaction of relativistic electric fields on moving charges
b. from a region of Magnesia, a province of Italy
c. from a region of Magnesia, a province of Greece
d. the Latin term for "attraction of metal"
e. the Latin term for "electron"
a
52. The first stones that were found to have magnetic qualities were called:
a. lodestones b. iron ore c. nickelodeon d. bodestones e. loderocks
c
53. Who were the first to use magnets for a compass?
a. French b. Italians c. Chinese d. Americans e. Indians
a
54. Who was the scientist who first made artificial magnets by rubbing pieces of iron against magnetic rocks?
a. William Gilbert
b. John Mitchell
c. Hans Christian Oersted
d. Andre-Marie Ampere
e. Mr. Smith
c
55. Which scientist was credited with finding out magnetic forces obey the inverse square law?
a. William Gilbert
b. Hans Christian Oersted
c. John Mitchell
d. Andre-Marie Ampere
e. Mr. Smith
a
56. Which scientist discovered that an electric current affects a magnetic compass?
a. Hans Christian Oersted
b. William Gilbert
c. John Mitchell
d. Andre-Marie Ampere
e. Mr. Smith
c
57. Suppose a magnet exerts an attractive force of 16 N on another magnet while placed 5 cm from it.
What will be the force if the magnets are 10 cm apart?
a. 8 N b. 32 N c. 4 N d. 0 N e. 256 N
a
58. Suppose a magnet exerts an attractive force of 16 N on another magnet while placed 5 cm from it. What
will be the force if the magnets are 20 cm apart?
a. 1 N b. 32 N c. 4 N d. 0 N e. 8 N
c
59. What are the poles of a magnet called?
a. east and west
b. positive and negative
c. north and south
d. electron and proton
e. north and west
a
60. What is the main difference between electric charges and magnetic poles?
a. electric charges can be isolated, magnetic poles cannot be isolated
b. electric charges cannot be isolated, magnetic poles can be isolated
c. electric charges both attract and repel, magnetic poles only attract
d. electric charges both attract and repel, magnetic poles only repel
e. magnetic poles both attract and repel, electric charges only repel
c
61. What would happen if you broke a bar magnet into 8 pieces?
a. you would have 8 half magnets
b. you would have 4 complete magnets
c. you would have 8 complete magnets
d. you would get into trouble with the teacher
e. you would destroy all magnetic properties of the original magnet
a
62. The space around a magnet contains what?
a. a magnetic field
b. mostly nitrogen, with some oxygen and other various gasses
c. nothing
d. an electric field
e. an anti-gravitational field
c
63. When looking at iron filings that have been allowed to interact with a magnetic field, what does the
density of lines suggest?
a. nothing
b. that the magnetic field is weakest there
c. that the magnetic field is strongest there
d. that the electric field is un-canceled there
e. that the electric field is the strongest there
a
64. Is magnetism related to electricity?
a. yes b. no
c
65. What condition is necessary for an electric charge to have a magnetic field around it?
a. it must be in a copper wire
b. it must be isolated from the opposite charge
c. it must be moving
d. it must be motionless
e. it must only be positive, a proton
a
71. For most magnetic materials, electron _________ is the main contributor to magnetism.
a. electron spin
b. electron orbital motion
c. proton spin
d. proton orbital motion
a
72. Is it correct to say that every electron spinning on its axis is a tiny magnet?
a. yes b. no
d
73. Why are most materials not magnetic?
a. they do not conduct electricity
b. they conduct electricity
c. they are not metals
d. the magnetic fields produced by the electron spin is canceled
e. they are insulators, meaning that electrons are not free to move around in the atomic lattice
b
74. In rare earth magnets, such as gadolinium or neodymium what is the main contributor to the magnetic
field?
a. electron spin
b. electron orbital motion
c. proton spin
d. proton orbital motion
d
75. Which is not a material that is commonly used to make a magnet?
a. iron b. cobalt c. nickel d. copper
b
76. When you put a compass around a steel can that has been in a closet, and it shows deflection, what
caused the can to become magnetic?
a. proximity to a powerful magnet
b. existence in the Earth's magnetic field
c. all steel is a magnet
d. no guess
b
77. What do you call a group of about a billion or so iron atoms that have their magnetic orientation
coordinated?
a. magnetic field b. magnetic domain c. magnetic flux d. Faraday
b
78. If you had a billion iron atoms grouped together, could you see it without magnification?
a. yes b. no
c
79. All pieces of iron have magnetic domains, why are most iron nails not magnetic?
a. they cannot conduct electricity
b. their domains are all oriented with respect to magnetic poles
c. their domains are randomly oriented, canceling out most magnetic forces
d. their atoms contain 4 electrons that spin magnetism is un-cancelled
b
80. When you bring a powerful magnet near an unmagnetized iron nail, what happens to the iron nail?
a. it conducts the magnetic field, similar to electricity in a copper wire
b. the magnetic domains in the nail align and the nail itself becomes a magnet
c. the magnetic domains of the magnet are pulled out of alignment, causing the nail to heat up\
d. nothing, there is no real change in the nail
a
81. What causes the temporary magnetism of a common iron nail to go away when the magnetizing force is
removed?
a. ordinary thermal motion
b. it never was a magnet
c. vibrations set off by the aligning domains, they can be heard with a amplified stethoscope
d. magic
e. the polar nature of the water molecule causes charges to leak off into the atmosphere
a
82. If a proton is moving through a vacuum at 1000 mph, is there a magnetic field being produced?
a. yes
b. no
c. only if the paired neutron is stationary
d. only if the paired electron is stationary
e. only if the paired electron is moving with the proton
b
83. Would a moving neutron produce a magnetic field?
a. yes b. no
a
84. Does a moving electron produce a magnetic field?
a. yes b. no c. depends
b
85. A current of charges produces what?
a. an amp b. a beam of light c. a magnetic field d. electricity e. ohms
c
86. What happens to the magnetic field intensity if the current carrying wire has three times as many loops,
and the same amount of current?
a. it is 1/3 as strong
b. it is nine times stronger
c. it is three times stronger
d. it doesn't change
e. it is 1/9 as strong
c
87. What do you call a rod of iron surrounded by a coil of current carrying wire?
a. a condenser
b. a magnetic domain
c. and electromagnet
d. an alternator
e. a generator
e
88. What does a moving charged particle experience if it moves through a static magnetic field?
a. nothing
b. an acceleration in the current direction
c. a deflection that is parallel to the magnetic field
d. a deflection that is perpendicular to the current and parallel to the magnetic field
e. a deflection that is perpendicular to both the magnetic field and the current
d
89. What would be the deflecting force of a 10 amp current running parallel to the magnetic field?
a. 10 N b. 100 N c. 1 N d. 0 N e. 1/10 N
a
90. What do you call a device that is used to measure current in a wire?
a. galvanometer
b. electroscope c. current meter
d. cathode ray tube (CRT)
c
91. If a galvanometer is calibrated to measure current, what is it called?
a. voltmeter
b. current-meter
c. ammeter
d. ampmeter
e. amperage
a
92. If a galvanometer is calibrated to measure electric potential, what is it called?
a. voltmeter
b. potentiometer
c. ammeter
d. ampmeter
e. amperage
a
95. What happens when a wire is moved close to a magnet?
a. current is induced
b. voltage is induced
c. nothing
d. everything
d
The induced voltage in a coil is proportional to the number of loops, multiplied by the rate at which the
magnetic field changes within those loops.
96. Whose law is written above?
a. Einstein's special theory of relativity
b. Ampere's Law
c. Electromagnetic Induction Law
d. Faraday's Law
e. Henry's Law
c
97. According to the above law, what would happen if the number of coils were doubled and the rate of
magnetic field changes tripled?
a. 2 times as much voltage
b. 3 times as much voltage
c. 6 times as much voltage
d. 2/3 times as much voltage
e. 3/2 times as much voltage
c
98. How does the voltage induced upon two equal coils, one made of copper and one made of rubber, differ?
a. voltage in copper much greater
b. voltage in rubber much greater
c. voltage is the same
d. no voltage at all in rubber
e
100. Suppose you had a generator that produced an induced voltage of 120 volts. Now suppose that the
internal resistance due to the coil was 10 Ω and the circuit connected had a total resistance of 20 Ω, what would
an ammeter read in the circuit?
a. 60 amps b. 40 amps c. 4 volts d. 12 amps e. 4 amps
YOU MIGHT ALSO LIKE...