Charge, current and potential difference

Charge, current and potential difference:

Current is the rate of flow of charge. I = Q/t, where I is the current (in amps), Q is the charge (in coulombs) and t is the time (in seconds).

The coulomb is the unit of charge (as seen above). You can use Q = It again to define it - one coulomb of charge is when 1 amp of current passes a given point every second.

Charge is usually carried by electrons, although it can also be carried by ions. Electrons all carry the same charge each - the elementary charge, 1.6 x 10^-19.

To make electric charge move through a circuit, work needs to be done on it. Potential difference (or voltage) is the work done per charge moved - V = W/Q, where V is the p.d. (in volts) and W is the work done (in joules).

The…