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Transformers

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Parts of a transformer

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Using a transformer to 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.

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Investigating transformers

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Properties of transformers

Transformers transfer power between circuits. The design of a transformer determines the characteristics of the electricity flowing in its secondary circuit.

The frequency of the alternating current in the secondary circuit matches the primary circuit, but what about voltage?

The voltage in each circuit is related to the number of coils on each side of a transformer by the following formula:

primary voltage

secondary voltage

primary turns

secondary turns=

Vp

Vs

Np

Ns

=

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Calculating voltage