AnswersBMS_Favors_Grade 8 Physical Science_Sem B_25-26Unit Test

Unit Test — Unit test Answers

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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.
2
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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
3

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

A
nitrogen
B
nickel
C
paper
D
plastic
4

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
5

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.
6

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

Question illustration
A
1
B
2
C
3
D
4
7

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.
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

Frances drew a diagram to show electromagnetic induction.

Question illustration
A
Current
B
Magnetic field
C
Solenoid
D
Force on wire
10

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.
11

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
12

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.
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

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
15

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.
16

Potential difference is measured in which units?

A
volts
B
amps
C
currents
D
watts
17

Which statement describes a property of magnets?

A
Magnets repel objects that are made of iron.
B
Magnets attract sheets of paper.
C
Magnets attract or repel iron nails.
D
Magnets attract or repel other magnets.
18

Hiro rubs an inflated balloon on his hair, and his hair sticks to the balloon. As he moves the balloon away from his head, how does the electric force change?

A
The electric force increases because the balloon loses its charge.
B
The electric force increases because the distance increases.
C
The electric force decreases because the distance increases.
D
The electric force decreases because his hair loses its charge.
19

A bar magnet and a second object are hung from metal rods. The diagram below shows what happens when both objects are released.

Question illustration
A
an iron bar
B
a steel bar
C
a bar magnet with its north pole on the left
D
a bar magnet with its south pole on the left
20

Which is produced around a wire when an electrical current is in the wire?

A
magnetic field
B
solenoid
C
electron flow
D
electromagnet

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