GCSE Physics (AQA)

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Calculating Resistance

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Electricity Current, potential difference and resistance

Calculating Resistance

2:41 Potential Difference and Resistance
Spec 4.2.1.3
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  • Current through a component is determined by its resistance and the potential difference across it.
  • The equation for this relationship is potential difference = current x resistance (V = I x R), known as Ohm's Law.
  • Units: potential difference in volts, current in amps, resistance in ohms.
  • Example 1: A component with 1 ohm resistance has a potential difference of 1 volt when 1 amp of current flows through it.
  • Example 2: For a variable resistor set to 15 ohms with a current of 0.2 amps, the potential difference is calculated as 3 volts.
  • Example 3: An electric heater with a potential difference of 230 volts and a current of 5 amps has a resistance of 46 ohms.
  • Steps for calculations:
  • Write down key information and check units.
  • Use the formula to calculate potential difference or rearrange it to find resistance.
  • Substitute values into the formula to get the result.

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