ALTERNATING CURRENT AND DIRECT CURRENT
4 marks · NormalA table lamp is rated at 60 W and is connected to a 240 V mains supply.
Calculate the current in the lamp when it is operating at full power.
Calculate the energy transferred if the lamp is left on for 30 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.
Show answer
(a) 0.25 A
(b) 108,000 J
Common mistakes: Forgetting to convert minutes to seconds; Incorrect formula rearrangement
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Uses formula or equivalent correctly. (follow-through)
A1 (a) · 1 mark · Substitutes values correctly and calculates . (follow-through)
M2 (b) · 1 mark · Uses formula . Converts 30 min to seconds if needed. (follow-through)
A2 (b) · 1 mark · Correct calculation of . (follow-through)
Worked solution
a) Power
b) Time in seconds: