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Magnetism and Electromagnetism — Test Answers

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1
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What is the direction of the magnetic field at point Z?

A
up
B
right
C
left
D
down
2
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Which functions belong in the cells marked X and Y?

A
X: Allows current to flow into the commutator Y: Conducts current to the armature and reverses direction of current
B
X: Rotates as a result of changing magnetic forces Y: Conducts current to the armature and reverses direction of current
C
X: Conducts current to the armature and reverses direction of current Y: Rotates as a result of changing magnetic forces
D
X: Allows current to flow into the commutator Y: Rotates as a result of changing magnetic forces
3

As Keisha runs the generator, which best describes what should happen to the needle that measures electric current?

A
It will move to a large negative value and stay there.
B
It will move to a large positive value and stay there.
C
It will move back and forth between a large positive and a large negative value.
D
It will move back and forth between 0 and a large positive value.
4

Which pair of magnets is aligned so they will repel each other?

A
W
B
Z
C
Y
D
X
5

What is the best conclusion that can be drawn?

A
A current flows down the wire.
B
A current flows up the wire.
C
A current flows, but its direction cannot be known.
D
A current does not flow in the wire.
6

What change would enable Gazala to pick up eight paper clips?

A
reversing the nail and using the nail’s head
B
reversing the battery
C
unwrapping several loops of the wire from the nail
D
wrapping the wire around the nail more times
7

What is the direction of the magnetic field at point Z?

A
into the screen
B
left
C
right
D
out of the screen
8

Based on the data, which prediction should he expect to occur?

A
A2 repels B1.
B
A1 attracts C2.
C
B1 repels C1.
D
C2 attracts B2.
9

A point charge of 6 point 8 mu cap c moves at 6 point 5 times 10 to the 4th power m/s at an angle of 15 degrees to a magnetic field that has a field strength of 1 point 4 cap t What is the magnitude of the magnetic force acting on the charge?

A
6 point 0 times 10 inverse cap n
B
6 point 0 times 10 to the 5th power cap n
C
1 point 6 times 10 inverse cap n
D
1 point 6 times 10 to the 5th power cap n
10

The voltage across the secondary winding is 10,000 V, and the voltage across the primary winding is 25,000 V. If the primary winding has 200 coils, how many coils are in the secondary winding?

A
125 coils
B
500 coils
C
50 coils
D
80 coils
11

Which describes the magnetic field that forms when a wire carries an electric current?

A
It is in a line perpendicular to the wire.
B
It is in a line parallel with the wire.
C
It is in a cylinder across the wire.
D
It is in a cylinder around the wire.
13

A current in a wire increases from 2 cap A to 6 cap A How will the magnetic field 0 point 0 1 m from the wire change?

A
It decreases to one-fourth its original value.
B
It increases to four times its original value.
C
It increases to three times its original value.
D
It decreases to one-third its original value.
14

Which describes Hans Oersted’s work with electricity and magnetism?

A
He discovered electromagnetism after seeing a compass needle deflected by a flowing electric current.
B
He discovered electromagnetic induction after seeing a changing magnetic field generate an electric current.
C
He discovered electromagnetism after seeing a changing magnetic field generate an electric current.
D
He discovered electromagnetic induction after seeing a compass needle deflected by a flowing electric current.
16

While researching magnetic fields, Marisa finds several online sites that describe a fictitious north monopole that is a magnet with only a north pole. Although it does not exist, the north monopole is used to describe magnetic field lines. Which statement best describes how the monopole would be used to describe magnetic field lines?

A
The field lines around a magnet point from the north pole to the south pole to show the direction of the magnetic force on the monopole.
B
The field lines around a magnet point from the north pole to the south pole to show the direction opposite to the magnetic force on the monopole.
C
The field lines around a magnet point from the south pole to the north pole to show the direction opposite to the magnetic force on the monopole.
D
The field lines around a magnet point from the south pole to the north pole to show the direction of the magnetic force on the monopole.
17

Pedro uses a bar magnet to pick up a nail. He then touches the tip of the nail to some staples. Why do some of the staples stick to the nail?

A
The nail has become a temporary magnet, while the bar magnet remains a permanent magnet.
B
The nail has become a permanent magnet, while the bar magnet has become a temporary magnet.
C
The nail and the bar magnet are now both permanent magnets.
D
The nail and the bar magnet are now both temporary magnets.
18

The magnetic field 0 point 0 2 m from a wire is 0 point 1 cap t What is the magnitude of the magnetic field 0 point 0 1 m from the same wire?

A
0 point 1 cap t
B
0 point 2 cap t
C
0 point 0 5 cap t
D
0 point 0 1 cap t
19

Craig is modeling the discovery of electromagnetism. Which procedure should he use?

A
moving a magnet into a coil of wire in an open circuit
B
bringing a compass near a wire that has an electric current
C
bringing a compass near a wire that has no electric current
D
moving a magnet into a coil of wire in a closed circuit
20

Which device converts electrical energy into kinetic energy?

A
a step-down transformer
B
an electric motor
C
an electric generator
D
a step-up transformer
21

Which is the best procedure to make a permanent magnet?

A
placing a magnetically soft material in a strong magnetic field
B
placing a magnetically hard material in a strong magnetic field
C
placing a magnetically hard material in a weak magnetic field
D
placing a magnetically soft material in a weak magnetic field
22

Which is true of a step-down transformer but not a step-up transformer?

A
The primary winding has more coils than the secondary winding.
B
The core is made of iron and the coils are made of copper.
C
The core is made of copper and the coils are made of iron.
D
The primary winding has fewer coils than the secondary winding.

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