A steel wire of 1 mm^2 cross-sectional area having Young's modulus 2 × 10^11 N / m^2 is stretched between two fixed points at a temperature of 40^°…

A steel wire of $\displaystyle 1 \mathrm{~mm}^2$ cross-sectional area having Young's modulus $\displaystyle 2 \times 10^{11} \mathrm{~N} / \mathrm{m}^2$ is stretched between two fixed points at a temperature of $\displaystyle 40^{\circ} \mathrm{C}$. The tension developed in the wire when its temperature falls to $\displaystyle 30^{\circ} \mathrm{C}$ is given by (Coefficient of linear expansion of steel $\displaystyle =11 \times 10^{-6} /{ }^{\circ} \mathrm{C}$ )