Electricity & Magnetism Vocabulary

Current

Flow of electric charge. Measured in amperes (A) with an ammeter connected in series.

Voltage (potential difference)

The ‘push’ or energy difference that drives current around a circuit. Measured in volts (V) with a voltmeter in parallel.

Resistance

Opposition to the flow of current. Measured in ohms (Ω).

Conductor

Material that allows electric current to flow easily (e.g. metals).

Insulator

Material that does not allow current to flow easily (e.g. plastic, rubber, glass).

Series circuit

Circuit with one pathway for current. Current is the same everywhere; voltages add up.

Parallel circuit

Circuit with more than one pathway. Voltage is the same across each branch; currents add up.

Power (electrical)

Rate of energy transfer. P = V × I. Unit: watt (W).

Kilowatt-hour (kWh)

Unit of energy used on electricity bills. Energy (kWh) = power (kW) × time (h).

Static electricity

Build-up of electric charge on the surface of an insulator.

Magnetic field

Region around a magnet where magnetic forces can be detected. Field lines run from North to South.

Electromagnet

Temporary magnet made by passing an electric current through a coil of wire (often around an iron core).

Fuse

Safety device that melts and breaks the circuit if the current becomes too high.

Circuit breaker

Safety device that trips and breaks the circuit if the current is too high; can be reset.