Physics Mains Electricity

Alternating Current

Current repeatedly changes direction e.g mains

Direct Current

Current flows in a single direction e.g battery

Live Wire

Brown. Provides alternating potential difference from mains supply

Neutral

Blue. Completes circuit by carrying electricity out

Heating Effect of current

Electrons collide with positive ions and energy is wasted as heat

Fuse

Safety measure. If current exceeds fuse rating, fuse melts and stops the flow of current.

Circuit Breaker

Same as fuse. Uses electromagnets. Can be reset and current rating is more easily chosen / can be more specific

Earth Wire (6)

Safety mechanism in anything metal. Green + yellow striped wire. If short circuit, metal is now part of circuit. Electricity travels through earth wire to the ground. A huge current ensues. melts the fuse so no current can pass through.

Plastic Appliances

Don’t need earth wires as are double insulated. No risk of touching metal. Won’t get electricuted.

Picking fuse

Just above the working current