Transformers

• Change the size of the potential difference of an alternating current
• They have two coils of wire, joined with an iron core
• When an alternating p.d. Is applied across the primary coil, the iron core magnetises and demagnetises quickly. This changes the magnetic field and induces a current in the secondary coil.
• If the second coil is part of a complete circuit, this caused a current to be induced. The ratio between the primary and secondary potential differences is the same as the ratio between the number of turns on the secondary and primary coils
• Step up transformers step up the potential difference, they have more turns on the secondary coil than the primary coil
• Step down transformers decrease the potential difference, they have more turns in the primary coil than the secondary