**Current**

Electrical current is the rate of flow of charge in a circuit. Current (I) is measured in amps (A), using an ammeter.

**Charge**

Charge (Q) is measured in coulombs (C). Each electron carries a tiny amount of charge, 1.6 x 10^{-19} coulombs.

charge = current x time

(coulomb, C) (ampere, A) (second, s)

**Power**

Power (P) is the rate at which energy is transformed in a device, it is measure in watts (W). 1 watt means that 1 joule of energy is transformed in one second.

power = energy transformed

time

Power, potential difference and current are related by the following equation;

power = potential difference x current

The energy transformed is given by;

energy transformed = potential difference x charge