Energy and Voltage in Circuits
3 marks · NormalA heater is connected to a 230 V supply and draws a current of 4.0 A for 5 minutes. Calculate the total energy transferred by the heater in this time. Include units in your answer.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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276,000 J (±1000)
Also accept: E = I × t × V
Common mistakes: Wrong units for time; Forgetting to convert minutes to seconds; Multiplying by current only
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Uses E = Q × V or E = I × t × V.
M2 · 1 mark · Correctly finds total charge: Q = 4.0 × 300 = 1200 C.
A1 · 1 mark · Evaluates final energy, E = 1200 C × 230 V = 276,000 J (or equivalent by direct method).
Worked solution
Time = 5 min = 5 × 60 s = 300 s
Or: E = I × t × V = 4.0 × 300 × 230 = 276,000 J