AnswersPhysicsApplications of Electromagnetic Induction

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In a step-down transformer, which describes the primary winding compared with the secondary winding?

A
lower voltage and more coils of wire
B
higher voltage and more coils of wire
C
higher voltage and fewer coils of wire
D
lower voltage and fewer coils of wire
2
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Which component is found only in electric generators and not in electric motors?

A
brushes
B
an armature
C
a commutator
D
slip rings
3

Which is an important step in how an electric motor uses magnetic force to produce motion?

A
As the north pole of the electromagnet nears the south pole of the permanent magnet, the current reverses and the poles of the magnets then repel.
B
As the north pole of the electromagnet nears the north pole of the permanent magnet, the current reverses and the poles of the magnets then repel.
C
As the north pole of the electromagnet nears the north pole of the permanent magnet, the current reverses and the poles of the magnets then attract.
D
As the north pole of the electromagnet nears the south pole of the permanent magnet, the current reverses and the poles of the magnets then attract.
5

Which best describes the steps involved in the operation of an electric generator?

A
The electric current passes from the slip rings, through the brushes, and to the collection device.
B
The electric current passes from the commutator, through the brushes, and into the power source.
C
The electric current passes from the power source, through the brushes, and into the commutator.
D
The electric current passes from the brushes, through the slip rings, and to the collection device.
6

What parts are found in an electric generator? Choose four correct answers.

A
slip rings
B
a permanent magnet
C
a battery
D
an electromagnet
E
brushes
F
an armature
7

Which best describes what happens in an electric generator?

A
Constantly changing magnetic fields lead to motion, which induces electrical energy.
B
Constantly changing magnetic fields lead to motion, which induces kinetic energy.
C
Motion causes constantly changing magnetic fields to induce kinetic energy.
D
Motion causes constantly changing magnetic fields to induce electrical energy.
8

How does an electric motor use magnetic force to produce motion?

A
The north pole of an electromagnet placed in the center of a permanent magnet attracts the north pole of the permanent magnet.
B
The north pole of an electromagnet placed in the center of a permanent magnet repels the north pole of the permanent magnet.
C
The north pole of a permanent magnet placed in the center of an electromagnet repels the north pole of the electromagnet.
D
The north pole of a permanent magnet placed in the center of an electromagnet attracts the north pole of the electromagnet.
9

How does an electric generator work?

A
The axle rotates the armature in the magnetic field of a permanent magnet, which induces an electric current.
B
The armature rotates the axle in the magnetic field of an electromagnet, which induces an electric current.
C
The axle rotates the armature in the magnetic field of an electromagnet, which induces an electric current.
D
The armature rotates the axle in the magnetic field of a permanent magnet, which induces an electric current.
10

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
2400 V
B
15,000 V
C
120 V
D
120,000 V

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