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TransformersLOs:

Know what an alternating current is.

See a transformer in operation.Use the transformer equation.

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Homework

Read the article from the Times

about wind power by next

lesson.

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Alternating Current

DC direct current what we get

from a battery.

All the electrons move around the circuitlike water in a pipe.

AC alternating current what we

get from the mains.

The electrons move backwards andforwards about 50 times a second.

We will see why in a minute

Animation!!!

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Electromagnets

Draw a picture of an

electromagnet. Include:

Coil of wire.

Core.

Magnetic field lines.

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Electromagnets

In electromagnets, the current

in the coil makes a magnetic

field.

If we have an alternating

current, the field keeps

changing.

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Transformer

In a transformer there is a

second coil.

This works in the opposite way

to the first coil

The changing magnetic field

creates an alternating current.

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So

Coil 1

Changing current creates changing

magnetic field.

Coil 2

Changing magnetic field createschanging current.

DEMO

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Transformers the maths

N1 = Number of turns on coil 1

N2= Number of turns on coil 2

V1 = Voltage on coil 1

V2 = Voltage on coil 2

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Write a glossary for

these key words: Transformer

Alternating Current

National Grid

Step-up transformer

Step-down transformer