Alternating Current (ac) and Direct Current (dc)

Define Alternating Current and Direct Current:
- Alternating Current (AC) refers to the flow of electric charge that periodically reverses direction.
- Direct Current (DC) is the unidirectional flow, meaning it moves in one direction only.
Differences between AC and DC:
- The primary difference between AC and DC involves the direction of the flow of electrons.
- DC is a constant stream in the same direction while AC changes direction periodically.
- AC is the type of current most commonly used in households and commercial establishments, while DC is primarily used for specific functionalities such as battery charging, lower voltage requirements, and specialised applications.
Characteristics of AC:
- In the United Kingdom, the frequency of AC from the mains supply is 50Hz, meaning it changes direction 100 times per second.
- The alternating nature of the AC waveform can be depicted as a sine wave.
Characteristics of DC:
- DC is a constant, steady current that moves in one direction only.
- It originates from sources such as batteries, fuel cells or solar cells.
Converting between AC and DC:
- A device known as a rectifier is used to convert AC to DC.
- Inversely, an inverter is used to convert DC to AC.
Safety aspects with AC and DC:
- AC is generally considered riskier because the alternating nature can cause muscles to contract, making it hard to release an object causing electrocution.
- DC can be dangerous as well, but the consistent current doesn’t include the same muscle contraction risk as AC.
Functions and Applications:
- Most home appliances like kettles, ovens, and washing machines use AC as these need higher voltage levels.
- DC is usually found in low voltage operations such as phone chargers, laptops or battery-operated devices.

Remember frequency, potential difference, current, rectifier, inverter, AC, DC, and safety principles when preparing for topics involving “Domestic Electricity”.