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AQA · GCSE · Physics · Higher

Calculating Whisk Power from Current

Q01.5 3 marks

The current in the whisk is 500 mA. The resistance of the whisk is 640 Ω.

Calculate the power of the whisk.

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Marking points

  1. 1 Converts 500 mA to 0.500 A.
  2. 2 Uses P = I²R with the supplied resistance.
  3. 3 Gives the final power as 160 W.

Full-mark answer

Convert the current: 500 mA=0.500 A500\ \text{mA} = 0.500\ \text{A}. Then P=I2R=0.5002×640=160 WP = I^2R = 0.500^2 \times 640 = 160\ \text{W}.

Why this answer loses marks

Uses the milliamp value directly in the power equation.

Convert milliamps to amps before squaring the current.

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