Generating Flashcards

1
Q

How is a voltage induced onto a wire?

A
  • When a wire is held stationary between the poles of a magnet, there is no current in the wire.
  • If the wire is moved upwards, a voltage is induced in the wire and a current passes. The same thing happens if the magnet is moved downwards.
  • When the wire moves downwards or the magnet moves up, the induced voltage and current is in the opposite direction
  • Reversing the direction of the magnetic field also reverse the induced voltage and current direction.
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2
Q

When is a voltage induced?

A

A voltage is induced whenever a magnetic field changes.

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3
Q

What does the size of the induced voltage depend on?

A
  • The size of the induced voltage depends on the rate at which the magnetic field changes:
    • If the wire is moved slowly voltage is low.
    • If the wire is moved quickly voltage is high.
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4
Q

How is the magnetic field inside the coil produced in a power station?

A

By electromagnets. The electromagnet is made from the coils of wire (rotor wire) which are turned by the turbine.

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5
Q

Where is the AC current produced?

A

An AC current is produced in the stator coil which surrounds the rotor coil.

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6
Q

What happens when the speed of rotation in the electromagnet increases?

A
  • Increasing the speed of rotation of the electromagnet increases both the current induced in the stator coil and the frequency of the voltage generated.
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7
Q

What happens when the number of turns on the electromagnet increases?

A

Increasing the number of turns on the electromagnet increases the magnetic field and therefore a larger voltage is induced in the stator coil.

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8
Q

What is another way to generate electricity?

A

Some AC generators do have a rotating coil between the poles of a magnet.

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9
Q

Why is the output of the a generator AC?

A

As the coil rotates, the direction of the current in the coil reverse every half turn.

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10
Q

What is the purpose of slip rings?

A

Slip rings are connected to the ends of the coil to allow the coil to spin without winding the wire around itself.

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11
Q

What are brushes?

A

The brushes are contacts that touch the slip rings and complete the circuit.

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