**Question**

**A stress of 9.8 × 10 ^{6} N/m^{2} is applied to a wire and Young’s modulus is 10^{11} N/m^{2} find the percentage increase in length [Ans. 0.0098%]**

**Answer**

Stress = 9.8 × 10^{6} N/m^{2}

Young’s modulus = 10^{11} N/m^{2}

Young modulus = stress \over strain

⇒ strain = stress \over Young\ modulus

⇒ strain = 9.8 × 10^6 \over 10^11

⇒ Δl\over l = 0.000098

Percentage increase in length = Δl\over l×100

= 0.000098 × 100

= 0.0098 %