Transformers
A An electrical device that increases, or decreases, the potential difference (voltage) of an alternating current. is a device that can change the The potential difference (or voltage) of a supply is a measure of the energy given to the charge carriers in a circuit. Units = volts (V). This is the voltage between two points that makes an electric current flow between them. or The potential difference across a cell, electrical supply or electrical component. It is measured in volts (V). of an alternating current:
- a step-up transformer increases the voltage
- a step-down transformer reduces the voltage
Design and use of transformers
A basic transformer is made from two coils of wire, a primary coil from the alternating current (ac) input and a secondary coil leading to the ac output. The coils are not electrically connected. Instead, they are wound around an iron core. This is easily magnetised and can carry Area surrounding a magnet that can exert a force on magnetic materials. from the primary coil to the secondary coil.
When a transformer is working:
- a primary voltage drives an Also called ac. An electric current that regularly changes its direction and size. through the primary coil
- the primary coil current produces a magnetic field, which changes as the current changes
- the iron core increases the strength of the magnetic field
- the changing magnetic field induces a changing potential difference in the secondary coil
- the induced potential difference produces an alternating current in the external circuit