Alternating current and direct current
3 marks · EasyA small heater is labelled 240 V, 50 W.
(a)[2 marks]
Calculate the current in the heater.
(b)[1 mark]
The heater is switched on for 3 minutes. Calculate the total energy transferred.
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.
Show answer
(a) 0.21 A
(b) 9,000 J
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Rearranges formula to I = P / V or substitutes into correct formula.
A1 (a) · 1 mark · Accurate calculation of current (0.21 A). (follow-through)
A1 (b) · 1 mark · Correct calculation of energy (9,000 J).
Worked solution
a) Using I = P / V:
b) Convert 3 minutes to seconds: 3 × 60 = 180 s