Alternating current and direct current
3 marks · EasyA torch bulb is connected to a battery that supplies a voltage of 4.5 V and a current of 0.2 A.
(a)[1 mark]
Calculate the power of the bulb.
(b)[2 marks]
The bulb is turned on for 10 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) 0.9 W
(b) 540 J
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Uses P = I × V with correct substitution (0.2 × 4.5)
M1 (b) · 1 mark · Converts 10 minutes to seconds or uses correct time in calculation.
A1 (b) · 1 mark · Accurate calculation of energy transferred (540 J) (follow-through)
Worked solution
a) Using P = I × V:
b) First, convert 10 minutes to seconds:
Then use E = I × V × t: