Imagine a conductor, such as a copper wire to be a down hill road. If a truck filled with balls opens up on top of this hill the balls will rush down to the bottom of the hill. In this film you will see an example. The balls represent electrons, the height difference between the top and the valley represents the voltage. The number of balls that passes per second represents the current. Only difference is that electrons are “negative” balls each having a negative charge. Electric current is defined as the flow of positive charge, so the opposite of the electron flow. Some of the balls will bump into obstacles. This can be compared with resistance. A road without parked cars, fire hydrants or traffic signs will allow a higher flow rate because of less resistance.