Which of the following factors does not affect the electric resistance of wire?

1. Analyze the question You are asked which factor does not affect the electrical resistance of a wire.

2. Concept The resistance of a wire is given by:

R = ρL / A

where

• R = resistance (Ω)
• ρ = resistivity of the material (Ωm)
• L = length of the wire
• A = cross-sectional area

Resistivity ρ also depends on temperature. For metals, resistance increases as temperature rises.

3. Check each option

• A. Length: R ∝ L, so a longer wire has more resistance. This affects resistance.
• B. Mass: Mass does not appear in the formula. Mass depends on the volume and density of the wire, and two wires of equal mass can have very different resistances (one long and thin, the other short and thick). So mass is not a direct factor.
• C. Temperature: It changes ρ, so it affects resistance.
• D. Cross-sectional area: R ∝ 1/A, so a thicker wire has less resistance. This affects resistance.

4. Answer The factor that does not directly affect resistance is mass, which is option B.

5. Exam tip Remember the factors with the letters LATM: Length, Area, Temperature, Material. Mass is not on the list. Mass only matters indirectly, through length and area, and not on its own.