AnswersCrowley Credit Recovery Physics BUnit 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

Steel objects can become temporary magnets because they are mainly composed of which element?

A
carbon
B
iron
C
nickel
D
cobalt
4

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.
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

Which actions most likely cause the domains within a material to lose their alignment and become more randomized? Check all that apply.

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
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

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
17

The diagram shows an electric motor.

Question illustration
A
W
B
X
C
Y
D
Z
18

Which statement describes the magnetic field inside a bar magnet?

A
It points from north to south.
B
It points from south to north.
C
It forms loops inside the magnet.
D
There is no field within the magnet.
19

A student uses the right-hand rule as shown.

Question illustration
A
up
B
right
C
down
D
left
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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