The potential difference in a circuit is what causes current to flow through the circuit. The larger the potential difference, the faster the current will flow and the higher the current. The potential difference is the measure of the difference in voltage between two distinct points in a closed circuit. Potential difference also is known as p.d., voltage difference, voltage or electric potential difference. This measure also is the energy per unit charge that is required to move a charged particle from one point to another.

Determine the amount of current traveling through the circuit. This value is usually measured in amperes.

Measure the amount of resistance in the circuit. Resistance comes from a resistor, a device in the circuit or simply the amount of resistance from the conductor (wire) in the circuit.

Multiply the amount of the current by the amount of resistance in the circuit. The result of the multiplication will be the potential difference, measured in volts. This formula is known as Ohm's Law, V = IR.