Units (Electricity)
4 marks · EasyThe diagram shows a simple circuit with a lamp powered by a battery.
Calculate the energy transferred by the lamp in 60 seconds.
State the amount of electric charge that passes through the lamp in 60 seconds.
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) 360 J
(b) 30 C
Common mistakes: Using E = V × t; Using wrong formula for energy
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Uses E = V × I × t correctly.
A1 (a) · 1 mark · Correctly calculates energy: 12 × 0.5 × 60 = 360 J (with unit).
M2 (b) · 1 mark · Uses Q = I × t correctly.
A2 (b) · 1 mark · Correctly calculates charge: 0.5 × 60 = 30 C (with unit).
Worked solution
Given: V = 12 V, I = 0.5 A, t = 60 s.
a) Energy transferred E = V × I × t = 12 × 0.5 × 60 = 6 × 60 = 360 J
b) Charge Q = I × t = 0.5 × 60 = 30 C