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JEE Main202226 Jun 2022Morning ShiftPhysicsCurrent ElectricityActual

An aluminium wire is stretched to make its length, 0 . 4 % larger. The percentage change in resistance is

Options

  1. A0 . 4 %
  2. B0 . 2 %
  3. C0 . 8 %
  4. D0 . 6 %

Correct answer

C. 0 . 8 %

Step-by-step solution

Volume of wire having cross-sectional area A and length l is, V = A l Resistance of a wire is given by, R = ρ l A = ρ l V l = ρ l 2 V As change in length is small, ∆ R R × 100 % = 2 ∆ l l × 100 % = 2 × 0 . 4 % = 0 . 8 %

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