JEE Main 2024 Physics question
A wire of length L and radius r is clamped at one end. If its other end is pulled by a force F, its length increases by ℓ. If the radius of the wire and the applied force both are reduced to half of their original values keeping original length constant, the increase in length will become:
Answer: (C)
Solution
Δℓ = Fℓ/(YA) ∝ F/A ∝ F/r². Halving both F and r gives (1/2)/(1/4) = 2, so the increase in length becomes 2 times.