Current

The flow of electrons in a wire can be compared to the flow of water in a pipe. The water current is the number of water molecules flowing past a fixed point. Electrical current is the number of electrons flowing past a fixed point. Current is measured in amperes or amps (A). One ampere is 6.25 X 10¹⁸ electrons per second passing through a wire. This number is just a short way of writing 6,250,000,000,000,000,000.

Think about water that flows through a pipe. As the diameter of the pipe increases (right image below), so does the amount of water that can flow through it. With electricity, a wire takes the place of the pipe. As the cross-sectional area of the wire increases, so does the amount of electric current (number of electrons) that can flow through it.