A transformer changes the voltage of an electric current while transferring it from one circuit to another through electromagnetic induction. Fluctuating magnetic fields in the transformer generate an electric current in a coil of wire, and the voltage they put out is directly proportional to the number of turns in the coil of wire.

Transformers have a structure called the “core” that usually contains iron. Two coils are wound around the core. One of the coils is called the primary coil, and the other is called the secondary coil. The primary coil is connected to a source of electric current. It is important that the source of current provides an alternating current in order to create a constant fluctuation in the magnetic field. The changing magnetic field induces another alternating current in the secondary coil, which is connected to a different electric circuit.

There are two types of transformers, depending on the voltage generated in the secondary coil relative to the voltage of the primary coil. The voltage generated in either coil is directly proportionate to the number of turns of the wire in that coil. If the secondary coil has more turns than the primary, then the output voltage is higher than the input voltage. This type of transformer is called a step-up transformer. If the secondary coil has fewer turns than the primary coil, then the output voltage is lower than the input voltage. These transformers are called step-down transformers. Transformers can be found in regular household appliances to ensure that the appliance receives the required voltage for operation.