Electricity
5 marks · NormalA 0.5 m length of wire has a current of 0.4 A flowing through it when a voltage of 2 V is applied across its ends.
Calculate the resistance of the wire.
If the current flows for 3 minutes, calculate the total charge passing through the wire.
Name the unit of electric charge.
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 Ω
(b) 72 C
(c) coulomb (C)
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Uses V = I × R and rearranges for R.
A1 (a) · 1 mark · Accurate calculation: R = 2 / 0.4 = 5 Ω. (follow-through)
M2 (b) · 1 mark · Uses Q = I × t, converts time to seconds.
A2 (b) · 1 mark · Accurate: Q = 0.4 × 180 = 72 C. (follow-through)
B1 (c) · 1 mark · Correct unit given (coulomb, C).
Worked solution
c. The unit is coulomb (C).