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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°C is: [For steel Young’s modulus is 2 × 10¹¹ N m⁻² and coefficient of thermal expansion is 1.1 × 10⁻⁵ K⁻¹]

1. 2.2 × 10⁸ Pa
2. 2.2 × 10⁹ Pa
3. 2.2 × 10⁷ Pa
4. 2.2 × 10⁶ Pa

Correct answer: 2.2 × 10⁸ Pa

Solution

The correct option is derived from the formula that relates thermal expansion and Young's modulus, which indicates that to maintain the original length of the wire despite temperature increase, a specific tensile stress must be applied. The calculated stress, based on the given values, results in 2.2 × 10⁸ Pa, making it the appropriate choice.

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