AnswersTX-Physics BUnit Test

Unit Test — Unit test Answers

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1
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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
2
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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
3

A current in a wire increases from 2 A to 6 A. How will the magnetic field 0.01 m from the wire change?

A
It increases to four times its original value.
B
It increases to three times its original value.
C
It decreases to one-fourth its original value.
D
It decreases to one-third its original value.
4

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
50 coils
B
80 coils
C
125 coils
D
500 coils
5

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
6

When the north pole of a bar magnet is moved into a solenoid, the needle on a galvanometer attached to the solenoid moves to the left, indicating that a current is produced. The magnet is then pulled out at a faster speed.What will be the result?

A
a larger current in the same direction
B
a larger current in the opposite direction
C
a smaller current in the same direction
D
a smaller current in the opposite direction
7

Four compasses are placed around a wire, as shown.

Question illustration
A
A current flows up the wire.
B
A current flows down the wire.
C
A current flows, but its direction cannot be known.
D
A current does not flow in the wire.
8

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.
9

Eva makes a graphic organizer to compare electromagnets with solenoids.

Question illustration
A
has a magnetic field like a bar magnet
B
has a metal core
C
uses electromagnetic induction
D
uses an electric current
10

Which changes will cause an increase in the magnetic field of a solenoid? Check all that apply.using more wire loopsusing fewer wire loopsusing a larger currentusing a smaller currentincreasing the spacing between loopsdecreasing the spacing between loops

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
11

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
12

fieldspolesdomainscurrents

A
fields
B
poles
C
domains
D
currents
13

Question text not available

Answer not available
14

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
15

A point charge of 5.7 µC moves at 4.5 × 105 m/s in a magnetic field that has a field strength of 3.2 mT, as shown in the diagram.

Question illustration
A
6.6 × 10–3 N
B
4.9 × 10–3 N
C
4.9 × 103 N
D
6.6 × 103 N
16

The generation of a magnetic field by an electric current is .

Answer not available
17

A bar magnet is placed on a table so that the north pole faces right.

A
They are pointing down into the table.
B
They are pointing right to left.
C
They are pointing left to right.
D
They are pointing up out of the table.
18

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.
19

A wire has a current that flows to the right.Which describes the magnetic field produced by the current?

A
straight lines along the wire to the right moving the same direction of the current
B
straight lines along the wire to the left moving the opposite direction of the current
C
circles around the wire that go in at the top of the screen and moves in a counterclockwise direction
D
circles around the wire that go in at the bottom of the screen and moves in a clockwise direction
20

fingerspalmbackthumb

A
fingers
B
palm
C
back
D
thumb

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