How do Transformers work?

Transformers are two coils of wire, coiled around each side of an iron core (primary and secondary). The primary coil has a potential difference supplied to it that drives the alternating current through the wire. This AC current induces a magnetic field which is also alternating (it is strengthened by the iron core), which then induces an AC current in the secondary coil which also creates a potentail difference in this coil. Transformers are used to change the potential difference along wires. They do this by making a different number of turns of coil on either side. If the secondary coil has more turns, the potentail difference induced is greater, whereas if it has less turns, the potential difference will be smaller. The following equation can be used to calculate the p.d. produced/ number of turns needed to produce a certain p.d. - p.d. across primary coil/ p.d. across secondary coil = no. of turns of primary coil / no. of turns of secondary coil.