Current, Potential difference and Resistance

The electric current in a circuit is determined by:

  • he potential difference (often referred to as voltage) from the power supply.
  • The resistance of the components in the circuit

Electrical work is done when an electric current flows through a circuit. We can calculate the current, potential difference or resistance using the equation:

  • V = Potential difference in volts (V)
  • I = Current in amperes (A)
  • R = Resistance in ohms (Ω)

It is not possible to directly change the electric current in a circuit, as the current is dependent on the potential difference and resistance.


Resistance is a measure of the opposition to the flow of current, which is measured in ohms (Ω). As you increase the resistance, it becomes more difficult for the current to flow through.

  • Conductors have a low resistance
  • Insulators have a high resistance

Ohm’s law states that the current is directly proportional to the potential difference, provided the temperature remains constant.