IP2.20.5 Potential difference in a series circuit

© Oxford University Press 2011

Potential differencein a series circuit

IP2.20.5 Potential difference in a series circuit

© Oxford University Press 2011

The potential difference of the supply is shared between the components in a series circuit. The sum of the potential differences across each component will equal the potential difference of the supply.

Think of two walkers climbing two mountains one after the other. The walkers have a certain amount of energy to climb both, they expend some energy climbing the first mountain which means their energy levels have reduced and they feel tired, then they climb the second mountain and expend more energy and feel more tired. By the end of the walk they have no energy left.

IP2.20.5 Potential difference in a series circuit

© Oxford University Press 2011

The components in this circuit have the following resistances:

Resistor 1 30 Ω

Resistor 2 50 Ω

Resistor 3 30 Ω

The voltage is shared across the components in proportion to their resistances.

R = 30 + 50 + 30 = 110 Ω

V1 = 11 × 30 / 110 = 3 V

V2 = 11 × 50 / 110 = 5 V

What are the p.d.s across each voltmeter?

IP2.20.5 Potential difference in a series circuit

© Oxford University Press 2011

Remember, for components connected in series: the total resistance is the sum of the resistance of each

component there is the same current through each component the total potential difference of the supply is shared between

the components.