CDS 2026 (I) General Knowledge, question 17

Topic: Physics

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Q17

Which one among the following statements regarding the electrical resistivity of a conducting wire is correct ?

  1. (a) The resistivity of the conductor increases if the length of the wire is increased.
  2. (b) The resistivity of the conductor decreases if the length of the wire is increased.
  3. (c) The resistivity of the conductor remains the same if the length of the wire is changed.Correct answer
  4. (d) The resistivity of the conductor increases if the cross-sectional area of the wire is increased.

Solution.

Answer: (c) The resistivity of the conductor remains the same if the length of the wire is changed.

  1. Resistivity is a material property at a specified temperature and physical state.
  2. Changing length or cross-sectional area changes resistance, not resistivity, provided the material and temperature are unchanged.
  3. R=ρLAR = \rho\frac{L}{A}