Physicshard · Past Paper
Two wires of the same material have lengths in ratio 1:2 and diameters in ratio 2:1. The ratio of their resistances is:
A1:4
B1:8
C1:1
D4:1
✓ Correct Answer: B — 1:8
R = ρL/A. R1/R2 = (L1/L2) * (A2/A1) = (1/2) * (d2^2 / d1^2) = (1/2) * (1/4) = 1/8.
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