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Transformer.
A transformer is made from two coils,
one on each side of a soft iron
core.
It can decrease the voltage (called a step down transformer)
or
increase the voltage (called a step up transformer,
shown below).
Alternating current is passed through the
primary coil (the input)
which creates a changing magnetic
field in the iron core.
The changing magnetic field then
induces
alternating current of the
same frequency in the secondary coil (the
output).
A step up transformer
has more turns of wire on the secondary
coil,
which makes a larger induced
voltage in the secondary
coil.
It is called a step up transformer because the voltage output
is larger than the voltage input.
If the secondary coil has twice as
many turns of wire
then the output voltage will be
twice the input voltage.
(continued).
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