Potential Difference (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award)): Revision Note

Potential difference

Extended tier only

• Potential difference is defined as:

  The work done by a unit charge passing between two points in a circuit

• Potential difference is measured in units of volts (V)

• The potential difference between two points in a circuit is related to the amount of energy transferred between those points

The potential difference is the difference in the electrical potential across each component: 5 volts for the bulb (on the left) and 7 volts for the resistor (on the right)

• As electrons flow through a cell, they gain energy

  • For example, in a 12 V cell, every coulomb of charge passing through gains 12 J of energy

• As electrons flow through a circuit, they lose energy

  • For example, after leaving the 12 V cell, each coulomb of charge will transfer 12 J of energy to the wires and components in the circuit

Electrons gain energy as they pass through a cell. As they flow through the light bulb, energy is transferred to the surroundings by heating and radiation