Answers3262 CR Physics B 2526Unit Test

Unit Test — Unit test Answers

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A coil of wire that carries an electric current is a(n) .

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2
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The presence of which magnetic feature best explains why a magnet can act at a distance on other magnets or on objects containing certain metals?

A
fields
B
dipoles
C
domains
D
forces
3

The voltage across the primary winding is 6000 V. If the primary winding has 50 coils and the secondary winding has 20 coils, what is the secondary voltage?

A
120 V
B
2400 V
C
15,000 V
D
120,000 V
4

A point charge of 5.0 × 10–7 C moves to the right at 2.6 × 105 m/s in a magnetic field that is directed into the screen and has a field strength of 1.8 × 10–2 T.

A
0 N
B
2.3 × 10–3 N
C
23 N
D
2.3 × 1011 N
5

The north pole of a strong magnet is dragged down an iron nail from the top to the point 50 times.

A
The nail will not pick up any paper clips because its domains are not aligned.
B
The nail will not pick up any paper clips because its domains have been aligned.
C
The nail will pick up some paper clips because its domains are not aligned.
D
The nail will pick up some paper clips because its domains have been aligned.
6

A wire runs left to right and carries a current in the direction shown.

Question illustration
A
left
B
right
C
into the screen
D
out of the screen
7

The table lists information about four devices.Which lists the devices in order from greatest magnetic field strength to weakest?

Question illustration
A
W, X, Y, Z
B
W, Z, Y, X
C
X, Z, Y, W
D
X, Y, Z, W
8

Which is an important step in how an electric motor uses magnetic force to produce motion?

A
As the north pole of the electromagnet nears the north pole of the permanent magnet, the current reverses and the poles of the magnets then attract.
B
As the north pole of the electromagnet nears the south pole of the permanent magnet, the current reverses and the poles of the magnets then repel.
C
As the north pole of the electromagnet nears the north pole of the permanent magnet, the current reverses and the poles of the magnets then repel.
D
As the north pole of the electromagnet nears the south pole of the permanent magnet, the current reverses and the poles of the magnets then attract.
9

The strength of a magnetic field around a wire carrying a current of 20 A is 0.004 T. What is the strength of the magnetic field if the current is changed to 40 A?

A
0.002 T
B
0.004 T
C
0.006 T
D
0.008 T
10

Which device converts electrical energy into kinetic energy?

A
an electric generator
B
an electric motor
C
a step-down transformer
D
a step-up transformer
11

What direction can the charge move and experience no magnetic force? Check all that apply.

A
up
B
down
C
left
D
right
E
into the screen
F
out of the screen
12

Which best describes what happens in an electric generator?

A
Motion causes constantly changing magnetic fields to induce electrical energy.
B
Motion causes constantly changing magnetic fields to induce kinetic energy.
C
Constantly changing magnetic fields lead to motion, which induces electrical energy.
D
Constantly changing magnetic fields lead to motion, which induces kinetic energy.
13

Two bar magnets are labeled A and B. The ends of each magnet are numbered 1 or 2, but the poles are not labeled. When A1 is brought near B1, the bars repel.

A
A1 is the north pole of a magnet, and B1 is the south pole of a magnet.
B
A1 is the north pole of a magnet, and B1 is the north pole of a magnet.
C
A1 and B1 are opposite poles, but there is not enough information to tell which ones.
D
A1 and B1 are like poles, but there is not enough information to tell whether they are north poles or south poles.
14

Which change would reverse the direction of the electric current generated through electromagnetic induction?

A
moving the magnet slower
B
using more loops of wire in the solenoid
C
using the opposite pole of the magnet
D
using a weaker magnet
15

The voltage across the primary winding is 350,000 V, and the voltage across the secondary winding is 17,500 V. If the secondary winding has 600 coils, how many coils are in the primary winding?

A
30 coils
B
583 coils
C
12,000 coils
D
332,500 coils
16

When using the right-hand rule to determine the direction of the magnetic force on a charge, which part of the hand points in the direction of the magnetic field?

A
palm
B
fingers
C
back
D
thumb
17

The diagram shows an electric motor.

Question illustration
A
W
B
X
C
Y
D
Z
18

Which actions most likely cause the domains within a material to lose their alignment and become more randomized? Check all that apply.heating the materialrubbing the material against a magnetpassing electricity around the materialplacing the material in a magnetic field of opposite polarityplacing the material near a strong magnethitting the material

A
heating the material
B
rubbing the material against a magnet
C
passing electricity around the material
D
placing the material in a magnetic field of opposite polarity
E
placing the material near a strong magnet
F
hitting the material
19

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

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

In a step-down transformer, which describes the primary winding compared with the secondary winding?

A
higher voltage and fewer coils of wire
B
higher voltage and more coils of wire
C
lower voltage and fewer coils of wire
D
lower voltage and more coils of wire

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