Electricity, Energy and Waves

Electric Current

The flow of charge (electrons) around a circuit, measured in amperes (A).

Charge (Q)

Measured in coulombs (C), charge is the quantity of electricity held by an object.

Potential Difference (Voltage)

The energy transferred per coulomb of charge, measured in volts (V).

Resistance (R)

Opposes the flow of current and is measured in ohms (Ω).

Ohm's Law

The relationship between voltage (V), current (I), and resistance (R), stated as V = I × R.

Series Circuit

A circuit where the current is the same at every point, total resistance adds up, and voltage is shared.

Parallel Circuit

A circuit where voltage is the same across each branch, total current is split, and resistance decreases.

Electrical Power (P)

The rate of energy transfer, calculated using P = V × I or P = I² × R.

Energy Transferred (E)

Calculated using E = P × t or E = V × Q, measured in joules (J) or kilowatt-hours (kWh).

Live Wire

The brown wire that carries voltage to the appliance in a circuit.

Neutral Wire

The blue wire that completes the circuit by returning current.

Earth Wire

The green/yellow wire that acts as a safety wire to prevent shocks.

Efficiency

A measure of how well energy is converted into useful output, calculated as Efficiency = (Useful energy output / Total energy output) × 100.

Kinetic Energy (KE)

The energy an object possesses due to its motion, calculated as KE = 0.5mv².

Frequency (f)

The number of waves that pass a point in one second, measured in hertz (Hz).