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NDA 1 2025 GAT, question 138

Topic: Physics

Q138

If the length of a copper wire is increased by twice, then its resistivity will be

  1. (a) Doubled
  2. (b) Halved
  3. (c) SameCorrect answer
  4. (d) One-fourth

Solution.

Answer: (c) Same

  1. Resistivity ρ\rho is a property of the material at a given temperature, not of the wire’s dimensions.
  2. Changing length changes resistance through R=ρL/AR = \rho L/A, but does not change resistivity if the material and temperature remain unchanged.