Question

When a tension $F$ is applied in uniform wire of length $\ell$ and radius $r$, the elongation produced is $e$.When tension $2F$ is applied, the elongation produced in another uniform wire of length $2\ell$ and radius $2r$ made of same material is :-

• A. $0.5e$
• B. $1.0e$
• C. $1.5e$
• D. $2.0e$

Answer 1

The correct option is B $1.0e$

$\begin{array}{c}\Delta l=e=\frac{Fl}{\pi r^{2}y}\\ \text{when}l=2\ell ,F=2F\text{and}r=2r\\ \text{elongation}=\frac{F\left(2l\right)}{\pi 4r^{2}y}\\ \text{elongation}=e\end{array}$