How Do Transformers Work?

Transformers are electrical devices that can change the potential difference across a circuit and so change the current flowing in the circuit. A transformer has two coils of wire wound on an iron core. Sometimes, the primary and secondary coils are wound side by side. In other transformers, one coil may be wound on top of the other.

An induced current can be generated in a coil provided that it is part of a complete circuit and provided that the magnetic field around the coil is changing.
This means that an alternating current in the primary coil of a transformer will produce a magnetic field which is always changing in the iron core and around the secondary coil. This induces an alternating potential difference across the ends of the secondary coil. The greater the number of turns in the secondary coil, the larger is the magnetic field and so the greater is the induced potential difference.

Basically transformers consist of two coils one being your incoming voltage and the other is either step up or step down depending on what outgoing voltage you need