A steel wire of length \(20 \mathrm{~cm}\) and area of crosssection \(1 \mathrm{~mm}^2\) is tied rigidly at both the ends. When the temperature of the wire is changed from \(40^{\circ} \mathrm{C}\) to \(20^{\circ} \mathrm{C}\), find the change in its tension. Given, the coefficient of linear expansion for steel is \(1.1 \times 10^{-5}{ }^{\circ} \mathrm{C}^{-1}\) and Young's modulus of steel is \(2.0 \times 10^{11} \mathrm{Nm}^{-2}\).

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.