Mains AC
- Mains electricity is the electricity generated by power stations and transported around the country through the National Grid
- Everyone connects to the mains when plugging in an appliance such as a phone charger or kettle
- Mains electricity is an alternating current (a.c.) supply
- In the UK, the domestic electricity supply has a frequency of 50 Hz and a potential difference of about 230 V
- A frequency of 50 Hz means the direction of the current changes back and forth 50 times every second
- Mains electricity, being an alternating current, does not have positive and negative sides to the power source
- The equivalent to positive and negative are called live and neutral and these form either end of the electrical circuit
The live and neutral wires deliver the electricity to the device. The Earth wire is purely for safety
Examiner Tip
You will be expected to remember the values of frequency and potential difference for mains electricity in the UK, so make sure you memorise these numbers:
- Frequency = 50 Hz
- Potential difference ~ 230 V