1. IP2.24.4 a.c. devices © Oxford University Press 2011 a.c. devices

2. IP2.24.4 a.c. devices © Oxford University Press 2011 All electrical devices use either alternating current (a.c.) or direct current (d.c.). Here are some devices that work with a.c. current.

3. IP2.24.4 a.c. devices © Oxford University Press 2011  Alternating current has a potential difference that switches smoothly between positive and negative values as part of a repeating cycle.  This causes the current to constantly change in size or reverse its direction very rapidly.  The mains supply in the UK is a.c.

4. IP2.24.4 a.c. devices © Oxford University Press 2011  The a.c. supply in the UK operates at 230V.  The frequency of the alternating current in the UK is 50 Hz. This is 50 cycles per second. Mains voltage used to be 240 V until in 1993 the UK standardised with the rest of Europe and set the voltage to 230 V.