Transformer

A transformer changes the size of an alternating potential difference. It does not create electrical energy. Instead, it transfers energy from one electrical circuit to another using a changing magnetic field.

A transformer changes the size of an alternating voltage. The voltage supplied to its primary coil is the input voltage, and the voltage produced across its secondary coil is the output voltage.

A transformer has an input primary coil and an output secondary coil. An alternating potential difference across the primary produces a changing magnetic field, which induces a potential difference across the secondary. The number of turns on each coil determines the ratio of their potential differences.

Power stations may be far from the homes and workplaces using their output, so the National Grid transfers electrical power across the country using cables and transformers.