Electric current

• Electric current is a flow of electrons. Each electron carries a very small amount of negative charge (1.6 x 10^-19 coulombs)

• A current of 1 amp at a point in a circuit is the flow of 1 coulomb of charge per second flowing past that point. This means that approx 6 x 10¹⁸ electrons must pass the point every second. This is a huge number.

• Electrons circulate continuously round a circuit being pumped round by a power source.

• If more than one route round the circuit is available then the electron flow will divide (in some ratio) between the available routes.

• Electrons will not be lost - all those that emerge from the power source will eventually return to it.

• To pump the current through any resistors in the circuit requires a voltage to be developed across them (think of it as a pressure difference required to push a fluid through a restriction)