A steel wire of cross-sectional area `0.5mm^2` is held between two fixed supports. If the wire is just taut at `20^@C`, determine the tension when the temperature falls to `0^@C`. Coefficient of linear expansion of steel is `1.2 xx 10^(-5 @)C(-1)` and its Young's modulus is `2.0 xx 10^11 N m^(-2)`.

Explanation

here final length is more than original length so that strain is tensile and tensile force is given by
`F = A Y alpha Delta t = 0.5 xx 10^(-6) xx2xx 10^(11) xx 1.2 xx 10^(-5) xx 20 = 24 N`