Transformers

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  • Created by: Char
  • Created on: 21-05-13 20:33
What does a transformer consist of?
Two coils of insulated wire
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What are these coils called?
The primary coil and the secondary coil
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Are they wound on the same iron core?
Yes
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When an alternating current passes through the primary coil, it produces what?
An alternating magnetic field in the core
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What does the magnetic field continually do?
Expands and collapses
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Which coil does the alternating magnetic field lines pass through?
The secondary coil
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And do what to the alternating potential difference across its ends?
Induce it
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What does the secondary coil have to be part of to produce an alternating current?
A complete circuit
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Why are the coils of wire insulated?
So that the current does not short across either the iron core OR adjacent turns of wire
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But flows instead around?
The whole coil
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Why is the core made of iron?
So it is easily magnetised
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What are transformers used in?
The National Grid
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Step up transformer =
Secondary coil GREATER THAN the pd across the primary coil (secondary coil has MORE turns than its primary coil)
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Step down transformer =
Secondary coil LESS THEN the pd across the primary coil (secondary coil has FEWER TURNS than its primary coil)
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What do transformers only work with - ac or dc?
AC
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Why?
Because DC would not be continually expanding and collapsing, so no potential diff would be induced in the secondary coil
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What is the switch mode transformer core made of?
Ferrite
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What is different of a switch mode transformer compared to a traditional transformer?
Operates at a higher frequency, is lighter and smaller and uses very little power when there is no device connected across its output terminals
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Other cards in this set

Card 2

Front

What are these coils called?

Back

The primary coil and the secondary coil

Card 3

Front

Are they wound on the same iron core?

Back

Preview of the front of card 3

Card 4

Front

When an alternating current passes through the primary coil, it produces what?

Back

Preview of the front of card 4

Card 5

Front

What does the magnetic field continually do?

Back

Preview of the front of card 5
View more cards

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