Topic Summaries

Potential difference and resistance

IGCSE > Physics > Pearson IGCSE > IGCSE Physics Topic Summaries > Potential difference and resistors > Potential difference and resistance
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Science skills: Measuring results

  • A current will only flow through a circuit when it has a source of potential difference (sometimes called a voltage). This will typically be provided by a cell or battery.
    • The electrons in the circuit are repelled from the negative terminal of the cell and attracted towards the positive terminal.
    • Potential difference is a measure of the electrical work done to move charge carriers through the circuit. It is measured in volts, V.
  • Resistance is a measure of how difficult it is to form a current for a particular potential difference.
    • Resistors are used in circuits to decrease the current through the whole circuit or in certain parts of it.
    • Resistance is measured in Ohms, Ω.
  • Current, potential difference and resistance in a component are related by the equation \(\text{potential difference}=\text{current}\times\text{resistance}\). This can also be written as \(V = IR\) where:
    • \(V\) is the potential difference across the component in V
    • \(I\) is the current in A
    • \(R\) is the resistance in Ω

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