AnswersOR-Science 8Unit Test

Unit Test — Unit test Answers

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1
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Aretha measures a circuit at 110 V and 240 . Using Ohm’s law, what can she calculate for the circuit?

Question illustration
A
voltage
B
ohms
C
resistance
D
current
2
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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
3

How does increasing the distance between charged objects affect the electric force between them?

A
The electric force increases because the distance has an indirect relationship to the force.
B
The electric force increases because the distance has a direct relationship to the force.
C
The electric force decreases because the distance has an indirect relationship to the force.
D
The electric force decreases because the distance has a direct relationship to the force.
4

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.
5

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.
6

An object that is made of which material is likely to be attracted to a magnet?

A
nitrogen
B
nickel
C
paper
D
plastic
7

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
8

The diagram shows a coiled wire that carries an electrical current.

Question illustration
A
the magnetic field
B
thermal energy
C
light energy
D
the electric field
9

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
10

Potential difference is measured in which units?

A
volts
B
amps
C
currents
D
watts
11

The image shows the electric field lines around two charged particles.

Question illustration
A
1
B
2
C
3
D
4
12

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
13

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.
14

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
15

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.
16

How are the current and resistance related when the voltage of a circuit is constant?

A
The current doubles when the resistance doubles because they are directly proportional.
B
The current doubles when the resistance doubles because they are inversely proportional.
C
The current is cut in half when the resistance doubles because they are directly proportional.
D
The current is cut in half when the resistance doubles because they are inversely proportional.
17

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.
18

Frances drew a diagram to show electromagnetic induction.

Question illustration
A
Current
B
Magnetic field
C
Solenoid
D
Force on wire
19

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
20

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.

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