Question

The length of a wire gets doubled on applying a stress of $20\times {10}^{8}N/m^2$. The Young's modulus of elasticity for the wire in $N/m^2,$ will be

• A. $40\times {10}^{8}N/m^2$
• B. $5\times {10}^{8}N/m^2$
• C. $10\times {10}^{8}N/m^2$
• D. $20\times {10}^{8}N/m^2$

Answer 1

The correct option is D $20\times {10}^{8}N/m^2$

Length gets double implies $\Delta l=lorStrain=\frac{\Delta l}{l}=1Thus,1=\frac{Stress}{Y}orY=Stress=20\times {10}^8$