The pressure that has to be applied to the ends of a steel wire of length 10cm to keep its length constant when its temperature is raised by `100^@C` is : (For steel Young's modulus is `2xx10^11 Nm^-2` and coefficient of thermal expansion is `1.1xx10^-5K^_1`)

Options

A. `2.2xx10^(7)` Pa
B. `2.2xx10^(6)` Pa
C. `2.2xx10^(8)` Pa
D. `2.2xx10^(9)` Pa

Answer

C

Explanation

As length is constant, strain `=(Delta l)/(l)=alpha Delta theta`
Pressure = stress = Y x strain `=Y alpha Delta theta`
`=(2xx10^(11))xx(1.1+10^(-5))xx(100)`
`2.2xx10^(8)Pa`