# 4.2.7 Potential Difference

### What is Potential Difference?

• As charge flows around a circuit, energy is transferred to or from the charge
• The potential difference (voltage) between two points in a circuit is related to the amount of energy transferred between those points in the circuit
• Potential difference is measure in volts (V) The potential difference is the voltage across each component: 5 volts for the bulb (on the left) and 7 volts for the resistor (on the right)

Extended Only

### Potential Difference & Energy

• The potential difference between two points in a circuit is the amount of energy transferred by each unit of charge passing between those two points
• The unit of voltage, the volt (V), is the same as a joule per coulomb (J/C)
`1 V = 1 J/C`
• So, for example:
• If a bulb has a voltage of 3 V, every coulomb of charge passing through the bulb will lose 3 J of energy

#### Exam Tip

Think of potential difference as being the energy per coulomb.

### Measuring Potential Difference

• Potential difference can be measured using a voltmeter
• The voltmeter should be connected in parallel with the part of the circuits you want to measure the potential difference of Potential difference can be measured by connecting a voltmeter between two points in a circuit ### Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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