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