ALTERNATING CURRENT AND DIRECT CURRENT
4 marks · NormalAn electric heater has a power rating of 1.2 kW and operates from a 240 V supply.
Calculate the current taken by the heater.
Calculate the energy transferred by the heater in 10 minutes.
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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(a) 5 A
(b) 720,000 J
Common mistakes: Forgetting to convert kilowatts to watts; Not converting minutes to seconds
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Marking points
M1 (a) · 1 mark · Converts power from kW to W (1.2 kW = 1200 W). (follow-through)
A1 (a) · 1 mark · Correct substitution and calculation for current (I = 5 A). (follow-through)
M2 (b) · 1 mark · Uses , converts time from min to s (10 min = 600 s). (follow-through)
A2 (b) · 1 mark · Correct calculation of energy J. (follow-through)
Worked solution
a)
b) 10 min = 600 s