Voltage and Current

Voltage as the amount of potential energy between two points on a circuit. One point has more charge than another. This difference in charge between the two points is called voltage. It is measured in volts.

Consider a water tank at a certain height above the ground. At the bottom of this tank there is a hose.

The pressure at the end of the hose can represent voltage. The water in the tank represents charge. The more water in the tank, the higher the charge, the more pressure is measured at the end of the hose.

Current is the amount of charge flowing through the circuit over a period of time. Current is measured in Amperes.

Consider two tanks, each with a hose coming from the bottom. Each tank has the exact same amount of water, but the hose on one tank is narrower than the hose on the other.


These two tanks create different pressures.


The amount of pressure is same at the end of either hose, but when the water begins to flow, the flow rate of the water in the tank with the narrower hose will be less than the flow rate of the water in the tank with the wider hose. In electrical terms, the current through the narrower hose is less than the current through the wider hose.

For the flow to be the same through both hoses, increase the amount of water (charge) in the tank with the narrower hose.

These two tanks create the same pressure.


This increases the pressure (voltage) at the end of the narrower hose, pushing more water through the tank. This is analogous to an increase in voltage that causes an increase in current.