QNEET-2024-Ph-69: NEET 2024 Physics - Class 11 NEET-2024-Ph-69 Solution: The maximum elongation of a steel wire of 1 m length if the…

First, we need to find the maximum force that can be applied to the steel wire within its elastic limit. This force can be calculated using the given area under stress and the stress limit provided by the elastic limit of steel. Let's assume the area of cross-section of the wire is A . The force exerted can be given by: F = _ _ A where: _ = 8 _ 10 8   N / m 2 (Elastic limit of steel) To calculate the elongation ( _ L ) under this force, we use Hooke's Law, which relates force, elongation, cross-sectional area, original length, and Young's modulus as follows: F = Y _ A _ _ L L where: Y = 2 _ 10 11   N / m 2 (Young's modulus of steel), L = 1   m (original length of the wire). Substituting for F from the earlier expression and rearranging the formula, we get: _ _ A = Y _ A _ _ L L _ = Y _ _ L L _ L = _ _ L Y _ L = 8 _ 10 8 _ 1 2 _ 10 11   meters _ L = 0.004   meters _ L = 4   mm Thus, the maximum elongation of the wire within the elastic limit is 4   mm . The answer is: Option A - 4 mm.