AnswersDCSS Physical Science CR 24-25Unit Test

Unit Test Answers

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Tisa makes a diagram to organize her notes about charging objects.

Question illustration
A
Electrons move between objects.
B
The objects do not touch.
C
The objects develop opposite charges.
D
The objects have the same charge.
2
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Georgia moves an unattached piece of wire back and forth over a magnet. Which best explains what will happen?

A
A current will be induced because the wire moves through a magnetic field.
B
A current will not be induced because the wire moves through a magnetic field.
C
A current will be induced because the wire is not part of a closed circuit.
D
A current will not be induced because the wire is not part of a closed circuit.
3

In a movie, a character cuts a wire, which stops the countdown timer of a bomb. What does cutting the wire do to the circuit?

A
It opens the circuit so that electric charges do not flow to the timer.
B
It closes the circuit so that electric charges do not flow to the timer.
C
It opens the circuit so that electric charges flow to the timer.
D
It closes the circuit so that electric charges flow to the timer.
4

What is the resistance of a clock if it has a current of 0.30 A and runs on a 9.0-V battery?

A
0.033
B
2.7
C
9.3
D
30
5

What causes the poles of the electromagnet in an audio speaker to repeatedly switch directions?

A
a metal striker that pulls on the magnet
B
a diaphragm that vibrates around the magnet
C
a current that rapidly switches direction
D
a device that opens and closes a circuit
6

What happens to an iron bar when it is placed within the coils of a solenoid?

A
It induces a current.
B
It stops the current.
C
It becomes a magnet.
D
It loses its magnetism.
7

Nina is working with electricity and shortens the wires through which the current is flowing. What is Nina most likely trying to accomplish?

A
convert electric energy to heat
B
convert electric energy to light
C
increase resistance
D
decrease resistance
8

Which will a positively charged object attract?

A
an object that has a negative charge
B
an object that has a smaller positive charge
C
an object that has no charge
D
an object that has a larger positive charge
9

Which would ultimately cause the armature in an electric motor to spin?

A
The current in the armature stops.
B
The gap in the commutator closes.
C
The current in the armature is reversed.
D
The commutator loses contact with the brushes.
10

Which statement correctly describes Earth’s magnetic field?

A
A compass can lead a hiker to the geographic North Pole.
B
The magnetic pole near the South Pole is a north pole.
C
Compasses point toward a magnetic pole that is a north pole.
D
Field lines circle Earth from east to west.
11

A bar magnet is cut in half, as shown. Which shows the pieces after the magnet is cut?

Question illustration
A
2 pieces of broken magnet with a jagged edge on the inside side of each piece. On the left a piece labeled N S from left and on the right a piece labeled N S from left.
B
2 pieces of broken magnet with a jagged edge on the inside side of each piece. On the left a piece labeled N S from left and on the right a piece labeled S N from left.
C
2 pieces of broken magnet with a jagged edge on the inside side of each piece. On the left a piece labeled N and on the right a piece labeled S.
D
2 pieces of broken magnet with a jagged edge on the inside side of each piece. On the left a piece labeled S and on the right a piece labeled N.
12

What is an advantage of series circuits?

A
Adding more batteries will increase the current.
B
There is more than one path for charges to flow.
C
If one bulb goes out, the other bulbs still shine.
D
Light bulbs get dimmer as more bulbs are added.
13

Ohm’s law describes the relationship between which quantities?

A
voltage, resistance, and ohms
B
resistance, current, and amperes
C
current, voltage, and resistance
D
amperes, ohms, and current
14

Cora, an electrician, wraps a copper wire with a thick plastic coating. What is she most likely trying to do?

A
keep the electric potential of the wire balanced
B
decrease the wire’s resistance
C
increase the voltage produced by the wire
D
keep a current from passing out of the wire
15

Frances drew a diagram to show electromagnetic induction.

Question illustration
A
Current
B
Magnetic field
C
Solenoid
D
Force on wire
16

Mateo makes a table of the symbols that represent the parts of an electric circuit.

Question illustration
A
Uses electrical energy
B
Provides electrical energy
C
Measures electric current
D
Controls electric current
17

What is required for an electric charge to flow through a wire?

A
zero resistance in the wire
B
a balance of electric potential
C
high resistance in the wire
D
a difference in electric potential
18

How are the magnetic field lines near the south pole of a magnet affected when a second south pole is brought near it?

A
The field lines combine with the lines around the second south pole.
B
The field lines overlap with the lines from the second south pole.
C
The field lines bend toward the second south pole.
D
The field lines bend away from the second south pole.
19

Potential difference is measured in which units?

A
volts
B
amps
C
currents
D
watts
20

Which parts of an electric generator are connected?

A
two brushes
B
two slip rings
C
the armature and axle
D
the armature and commutator

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