What is a transformer?

What is a transformer?
The voltage of an alternating current can be changed using
a device called a transformer.
A transformer contains two
coils that are wound around
a soft iron core.
iron core
The alternating current in
the primary (input) coil
produces an alternating
magnetic field.
This alternating magnetic
field induces an alternating
current in the secondary
(output) coil.
How does a transformer change voltage?
The voltage induced in the secondary (output) coil depends
on the number of turns on the primary and secondary coils.
A step-up transformer
has more turns on the
secondary coil and so
increases voltage.
A step-down transformer
has fewer turns on the
secondary coil and so
decreases voltage.
Where are transformers used?
A television needs a very high
voltage to operate. It contains
a step-up transformer,
which increases the voltage
of the electricity supplied to
the television.
This outdoor transformer
decreases the voltage of
the electricity carried by
the national grid. It is an
example of a step-down
How are transformers used to supply electricity?
How does electricity get to your home?

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