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Electromagnetism — Test Answers

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1
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Which best explains how the constants affect the electrical and gravitational forces?

A
The electrical force is much smaller than the gravitational force because 8 point 9 9 is much greater than 6 point 6 7 .
B
The electrical force is much larger than the gravitational force because 10 to the 9th power is much greater than 10 to the negative 11 power.
C
The electrical force is much larger than the gravitational force because 8 point 9 9 is much greater than 6 point 6 7 .
D
The electrical force is much smaller than the gravitational force because 10 to the 9th power is much greater than 10 to the negative 11 power.
2
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What should Isla write in the areas marked A, B, and C?

A
A: Has a higher frequency B: Can travel only through matter C: Has a longer wavelength
B
A: Has a longer wavelength B: Travels at the same speed C: Has a higher frequency
C
A: Has a longer wavelength B: Can travel only through matter C: Has a higher frequency
D
A: Has a higher frequency B: Travels at the same speed C: Has a longer wavelength
3

Which part of the motor is responsible for reversing the flow of current?

A
W
B
X
C
Y
D
Z
4

Which headings best complete the chart?

A
A: Infrared Waves B: cap x -rays
B
A: Ultraviolet Waves B: Gamma Rays
C
A: cap x -rays B: Radio Waves
D
A: Microwaves B: Ultraviolet Waves
5

A current in a wire increases from 2 cap A to 6 cap A How will the magnetic field 0 point 0 1 m from the wire change?

A
It increases to three times its original value.
B
It increases to four times its original value.
C
It decreases to one-fourth its original value.
D
It decreases to one-third its original value.
6

Craig is modeling the discovery of electromagnetism. Which procedure should he use?

A
bringing a compass near a wire that has an electric current
B
bringing a compass near a wire that has no electric current
C
moving a magnet into a coil of wire in an open circuit
D
moving a magnet into a coil of wire in a closed circuit
7

Which component in a nuclear power plant actually produces the electrical energy?

A
uranium
B
a generator
C
a turbine
D
steam
8

The magnetic field 0 point 0 2 m from a wire is 0 point 1 cap t What is the magnitude of the magnetic field 0 point 0 1 m from the same wire?

A
0 point 0 1 cap t
B
0 point 1 cap t
C
0 point 0 5 cap t
D
0 point 2 cap t
9

Pedro uses a bar magnet to pick up a nail. He then touches the tip of the nail to some staples. Why do some of the staples stick to the nail?

A
The nail and the bar magnet are now both temporary magnets.
B
The nail and the bar magnet are now both permanent magnets.
C
The nail has become a temporary magnet, while the bar magnet remains a permanent magnet.
D
The nail has become a permanent magnet, while the bar magnet has become a temporary magnet.
10

A pair of opposite electric charges of equal magnitude is called a(n)

A
dipole.
B
field line.
C
electric field.
D
point charge.
11

Which device converts electrical energy into kinetic energy?

A
a step-down transformer
B
a step-up transformer
C
an electric generator
D
an electric motor
12

What do all electromagnetic waves have in common?

A
They travel only through matter.
B
They have the same wavelengths.
C
They can travel at the speed of light.
D
They have nonmoving magnetic fields.
13

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 cylinder across the wire.
C
It is in a line parallel with the wire.
D
It is in a cylinder around the wire.
14

What do transformers do in the generation and distribution of electrical energy? Choose two correct answers.

A
increase voltage
B
turn turbines
C
turn generators
D
decrease voltage
E
convert water into steam
15

A charge of 6 point 4 times 10 to the negative 7 power cap c experiences an electric force of 1 point 8 times 10 inverse cap n What is the electric field strength?

A
2 point 8 times 10 to the 5th power cap n over cap c
B
1 point 1 times 10 to the negative 7 power cap n over cap c
C
8 point 2 times 10 to the 0 power cap n over cap c
D
3 point 6 times 10 to the negative 6 power cap n over cap c
16

A charge of 8 point 5 times 10 to the negative 6 power cap c is in an electric field that has a strength of 3 point 2 times 10 to the 5th power cap n over cap c What is the electric force acting on the charge?

A
270 cap n
B
2 point 7 cap n
C
0 point 2 7 cap n
D
27 cap n
17

Which is the best procedure to make a permanent magnet?

A
placing a magnetically soft material in a weak magnetic field
B
placing a magnetically soft material in a strong magnetic field
C
placing a magnetically hard material in a weak magnetic field
D
placing a magnetically hard material in a strong magnetic field
19

A magnetically soft material is placed in a strong magnetic field. What is the most likely outcome?

A
It will become a temporary magnet because the domains will easily realign.
B
It will become a permanent magnet because the domains will easily realign.
C
It will become a temporary magnet because the domains will remain aligned.
D
It will become a permanent magnet because the domains will remain aligned.
20

Which factors affect the electrical force between two objects?

A
charge and mass
B
mass and distance between them
C
charge and distance between them
D
mass and electric field strength
21

How does the electrical force relate to the charge of an object?

A
It is directly proportional to the square of the charge.
B
It is inversely proportional to the square of the charge.
C
It is directly proportional to the charge.
D
It is inversely proportional to the charge.

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