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Q51 (CDS-I/2021) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Electricity and magnetism Answer Verified

We are given three copper wires of different lengths and different areas of cross-section. Which one of the following would have highest resistivity ?

Result
Your answer: —  ·  Correct: D
Explanation

Electrical resistivity (ρ) is an intrinsic property of a material, meaning it depends solely on the nature of the material and its temperature, rather than its physical dimensions [1]. While the resistance (R) of a conductor is directly proportional to its length (L) and inversely proportional to its cross-sectional area (A) as defined by the formula R = ρL/A, the resistivity itself remains constant for a specific material [2]. In this scenario, all three wires are made of copper. Since the material is identical for all options, the resistivity will be the same regardless of the variations in length (50 cm, 25 cm, or 10 cm) or diameter (1 mm, 0.5 mm, or 2.0 mm). Therefore, all the copper wires possess the same resistivity.

Sources

  1. [1] https://sathee.iitk.ac.in/article/physics/difference-between-resistance-and-resistivity/
  2. [2] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > Activity 11.3 > p. 178
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