Physicshard · Past Paper
A wire of resistivity 'rho' is stretched so that its length increases by 10%. What is the approximate percentage increase in its resistance?
A10%
B20%
C21%
D100%
✓ Correct Answer: C — 21%
If L becomes 1.1L, Area becomes A/1.1 (constant volume). R' = ρ(1.1L)/(A/1.1) = 1.21 * R. Increase is 21%.
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