alternating current - Current whose direction changes many times each second., direct current - A current that flows in one direction only, such as the current produced by a battery., hertz - The unit for frequency, 1 hertz is one wave per second., mains electricity - Electricity supplied from power stations using the national grid., national grid - The system of wires and transformers that distributes electricity around the country., fuse - A safety device containing a length of wire that is designed to melt if the current in a circuit gets too hot., circuit breaker - A component that switches off the current if there is a fault and the current rises to dangerous levels. It is easy to switch back on when the fault is fixed., earth wire - A low-resistance path for electric current to flow to earth for safety if there is a fault in an appliance., live wire - The wire connected to the a.c. supply from the power station. The voltage oscillates between V_max in one direction and V_minin the opposite direction., neutral wire - A neutral wire is held at or near-earth potential (0 V). It completes the circuit to the power station and carries current.,

Electrical Safety

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