AnswersTX-Physics BLab: Electromagnetic Induction

Lab: Electromagnetic Induction — Unit test Answers

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1
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What parts are found in an electric generator? Select 4 options.

A
an armature
B
a battery
C
a permanent magnet
D
an electromagnet
E
brushes
F
slip rings
3
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The diagram shows a negative charge moving in a magnetic field.

Question illustration
A
right
B
left
C
into the screen
D
out of the screen
4

Four compasses are placed around a wire, as shown.The wire is then connected to a battery so that a current flows down the wire.How will the compasses point once the current is flowing?

Question illustration
A
A long wire that is vertical and standing on a steel plate. There are 4 compasses surrounding it and all of the needles are pointing in the same direction, west.
Option A
B
A long wire that is vertical and standing on a steel plate. There are 4 compasses surrounding it and all of the needles are pointing in the same direction, east.
Option B
C
A long wire that is vertical and standing on a steel plate. There are 4 compasses surrounding it and all of the needles are pointing clockwise.
Option C
D
A long wire that is vertical and standing on a steel plate. There are 4 compasses surrounding it and all of the needles are pointing counterclockwise.
Option D
5

Which component is found only in electric generators and not in electric motors?

A
a commutator
B
brushes
C
an armature
D
slip rings
6

A magnetically soft material is placed in a strong magnetic field.

A
It will become a permanent magnet because the domains will remain aligned.
B
It will become a temporary magnet because the domains will remain aligned.
C
It will become a permanent magnet because the domains will easily realign.
D
It will become a temporary magnet because the domains will easily realign.
7

How does an electric motor use magnetic force to produce motion?

A
The north pole of a permanent magnet placed in the center of an electromagnet attracts the north pole of the electromagnet.
B
The north pole of an electromagnet placed in the center of a permanent magnet attracts the north pole of the permanent magnet.
C
The north pole of a permanent magnet placed in the center of an electromagnet repels the north pole of the electromagnet.
D
The north pole of an electromagnet placed in the center of a permanent magnet repels the north pole of the permanent magnet.
9

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.
10

brushtransformercommutatorarmature

A
brush
B
transformer
C
commutator
D
armature
12

Which change will cause an increase in the electric current produced through electromagnetic induction?

A
using more wire loops in the solenoid
B
using the opposite pole of the magnet
C
using a weaker magnet
D
moving the solenoid slower
13

Tonya is modeling the discovery of electromagnetic induction. Which procedure should she 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
14

The magnetic field 0.02 m from a wire is 0.1 T. What is the magnitude of the magnetic field 0.01 m from the same wire?

A
0.01 T
B
0.05 T
C
0.1 T
D
0.2 T
15

Which is the best procedure to make a permanent magnet?

A
placing a magnetically hard material in a weak magnetic field
B
placing a magnetically hard material in a strong magnetic field
C
placing a magnetically soft material in a weak magnetic field
D
placing a magnetically soft material in a strong magnetic field
16

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 around the wire.
D
It is in a cylinder across the wire.
17

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
18

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
19

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
20

Which changes will cause an increase in the magnetic field of a solenoid? Check all that apply.

A
using more wire loops
B
using fewer wire loops
C
using a larger current
D
using a smaller current
E
increasing the spacing between loops
F
decreasing the spacing between loops
21

The diagram shows two bar magnets. They are cut along the dashed line, and then the two marked ends are placed near each other.

Question illustration
A
The pieces will repel because the cut end of the top magnet is not a magnetic pole.
B
The pieces will attract because the cut end of the top magnet is not a magnetic pole.
C
The pieces will repel because the cut end of the top magnet is a south pole.
D
The pieces will attract because the cut end of the top magnet is a north pole.
22

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
23

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

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