The pressure that has to be applied to the ends of a steel wire of length $10 \mathrm{cm}$ to keep its length constant when its temperature is raised by $100 °\mathrm{C}$ is :
(For steel, Young's modulus is $2\times {10}^{11} \mathrm{N} {\mathrm{m}}^{-2}$ and coefficient of thermal expansion is $1.1\times {10}^{-5} {\mathrm{K}}^{-1}$)