GCSE Combined Science (AQA)

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Electrical Power

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Electricity Energy transfers

Electrical Power

3:11 Electrical Energy and Power
Spec 4.2.4.1 4.2.4.2
Previous Electrical Safety Next Electrical Power in Terms of Resistance
  • Power output of an electrical component depends on current and potential difference.
  • Power is the rate of energy conversion from charge carriers into other forms.
  • Power is determined by energy given by a charge carrier and frequency of passage through the component.
  • Power equation: P = I x V (Power = Current x Potential Difference).
  • Current is measured in amps, potential difference in volts, and power in watts.
  • Example: Microwave with power output of 1200 watts and potential difference of 240 volts; calculate current.
  • Power ratings indicate safe range of potential difference and power for components.
  • To calculate current: Rearrange power equation to I = P / V.
  • Substitute values: Current = 1200 watts / 240 volts = 5 amps.
  • Increase power output by increasing current or potential difference.
  • Example: Increase bulb brightness by adding a cell or removing a resistor.
  • Adding a cell increases potential difference; removing a resistor decreases resistance and increases current.
  • Use resistors to prevent current from becoming too high.
  • Power increases with increased potential difference and current.
  • For exams, explain how changing potential difference, current, or resistance affects power.

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