# Potential Difference(Edexcel International A Level Physics)

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Joanna

Expertise

Physics

## Potential Difference

#### Potential Difference

• A cell makes one end of the circuit positive and the other negative
• This sets up a potential difference across the circuit
• This is sometimes known as the voltage

• The potential difference is defined as the work done per unit charge and is measured in units of volts (V)

#### Measuring Voltage

• Potential difference (or voltage) is measured using a voltmeter
• A voltmeter is always set up in parallel to (also called 'across') the component being measured
• Potential difference across components in parallel is always the same due to conservation of energy

Potential difference can be measured by connecting a voltmeter in parallel between two points in a circuit

#### Worked example

A resistor is connected to a battery which provides a potential difference of 10 V.

Calculate the work done when a charge of 2 C passes through the resistor.

Step 1: Write down the known quantities

• Potential difference, V = 10 V
• Charge, Q = 2 C

Step 2: Write down the equation relating potential difference, work done and charge

Step 3: Rearrange the equation to make work done the subject

Step 4: Substitute in the values and calculate W

#### Exam Tip

Think of potential difference as being the energy per coulomb of charge transferred between two points in a circuit

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