Question

The increase in length of a wire on stretching is $0.025$%. If its Poisson's ratio is $0.4$, then the percentage decrease in the diameter is :

• A. $0.01$
• B. $0.02$
• C. $0.03$
• D. $0.04$

Answer 1

The correct option is A $0.01$

$\text{Poisson's ratio}=\frac{\Delta d/d}{\Delta l/l}$
$0.4=\frac{\Delta d/d}{0.025/100}$
$\frac{0.4\times 0.025}{100}=\Delta d/d$
$\Delta d/d=0.01$ %