Question

An elongation of ${0.1}^{\circ }$ in a wire of cross sectional area ${10}^{-6}{m}^2$ causes a tension of 100n. The Young's modulus is-

• A. ${10}^{12}N/M^2$
• B. ${10}^{11}N/M^2$
• C. ${10}^{10}N/M^2$
• D. ${10}^{2}N/M^2$

Answer 1

Answer: (B)

${10}^{11}N/M^2$

Given,

$\frac{\Delta l}{l}\times 100=0.1$%

$\frac{\Delta l}{l}=\frac{0.1}{100}=1\times {10}^{-3}$

Cross-sectional area, $A={10}^{-6}{m}^2$

$T=100N$

Young's modulus,

$Y=\frac{T/A}{\Delta l/l}=\frac{100/{10}^{-6}}{{10}^{-3}}=\frac{100}{{10}^{-9}}$

$Y={10}^{11}N/m^2$

The correct option is B.