MCQ
If a wire is stretched to make it $0.1 \%$ longer, its resistance will
- Aincrease by $0.05 \% $
- ✓increase by $0.2 \%$
- Cdecrease by $0.2 \%$
- Ddecrease by $0.05 \% $
✓
Answer
Correct option: B.
increase by $0.2 \%$
b
Resistance of wire
Resistance of wire
$R=\frac{\rho l}{A}=\frac{\rho l^{2}}{C}(\text { where } A l=C)$
$\therefore $ Fractional change in resistance
$\frac{\Delta R}{R}=2 \frac{\Delta l}{l}$
$\therefore $ Resistance will increase by $0.2 \%$
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