Given, Young's modulus of steel wire, Y=2×1011Nm−2 Length of wire, l=20cm=0.2m Area of cross-section, A=1mm2=10−6m2 Change in temperature of wire, ∆t=(40−20)∘C =20∘C α=1.1×10−5∘C−1 ∴ Change in tension in the steel wire, T=YAα∆t