Question:easy

On which factor the resistance of a conductor does not depend?

Show Hint

For bulk DC conduction, charge flows uniformly through the entire cross-section of the conductor.
Hence, surface characteristics like polish or roughness do not alter the bulk resistance.
  • Its length
  • Its area of cross-section
  • Nature of its material
  • Its surface finish
Show Solution

The Correct Option is D

Solution and Explanation

Step 1: List what resistance is built from.
Resistance of a wire comes from the formula \[ R = \rho \frac{l}{A} \] so it is controlled only by the material (through \(\rho\)), the length \(l\), and the cross sectional area \(A\).
Step 2: Check each option against this formula.
Length appears directly in the formula, so it matters. Area appears directly too. The nature of the material fixes \(\rho\), so that matters as well. Surface finish, meaning how smooth or rough the outer surface looks, is not present anywhere in the formula.
Step 3: Physical reasoning.
Current flows through the bulk of the metal, through the free electrons moving inside the wire, not along its outer skin. A polished wire and a slightly rough wire of the same length, area and material conduct current equally well.
\[ \boxed{\text{Surface finish}} \]
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