Potential Difference

PhysicsAQAGCSEUnit: Electricity
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The basics

The Ski Lift Model

⚡ The Ski Lift Model

Think of a battery as a ski lift. It picks up skiers (charges) at the bottom and lifts them to the top, giving them gravitational potential energy. A 12 V battery gives 12 joules of energy to every coulomb of charge that passes through it. Components are like the ski slopes — they take energy from the charges as they pass through. A lamp with 12 V across it takes 12 joules from every coulomb. Voltage is just energy per charge — the "height" of the electrical "hill"!
Spotlight
Understanding Potential Difference

Potential difference (p.d.) is the energy transferred per unit charge as charges pass through a component.

Exam tip

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🧠 Memory Aid

For V = E/Q — the Ski Lift:

The Voltage is the Elevation (energy) given to each Quantity of charge (coulomb). The battery is the ski lift that raises each coulomb to a higher "energy height."

Voltmeter vs Ammeter connection — "V is a visitor, A is in the action":

The Voltmeter is a Visitor — it stands alongside (parallel), watching what happens across a component. The Ammeter is in the Action — it stands in the flow itself (series), part of the circuit.

Series vs Parallel voltage rule — "Series Shares, Parallel Pairs":

In a series circuit, the voltage is shared (split) between components. In a parallel circuit, every branch gets the same voltage as the supply.

Now try it yourself

Quiz · Question 1 of 14

Which of the following is the correct definition of potential difference?

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