There are two different types of current - AC and DC.
- AC = Alternating current. The current changes direction. In the UK this happens 50 times a second.
- DC = Direct current. The current only flows in one direction.
The mains electricity supply in the UK is AC - alternating current. Alternating current means that the current continually changes direction.
In the UK the electricity supply is 50Hz, this means that the direction of the current changes 50 times a second! The potential difference is 230V.
The other type of current is DC - direct current. This means that the current only flows in one direction.