Which of the following factors is not among that determines the resistance of a wire?

Analyze the question: We need the factor that does not determine the resistance of a wire.

Concept: The resistance of a uniform wire is given by

R = ρL / A

where:

• ρ = resistivity, which depends on the material (and temperature)
• L = length of the wire
• A = cross-sectional area

So resistance increases with length, decreases with a larger cross-sectional area, and depends on the material. Temperature also affects it.

Checking each option:

• A. Mass: Mass does not appear in the formula. It is not a direct determining factor. Two wires of different mass can have the same resistance if their ρ, L and A are the same. Mass is related to the wire's volume and density, but it is not an independent factor in resistance.
• B. Cross-sectional area: Appears in the formula, so it is a factor.
• C. Length: Appears in the formula, so it is a factor.
• D. Material: Determines resistivity ρ, so it is a factor.

Answer: The factor that is not among those determining resistance is mass, which is option A.

Tip: Remember "R = ρL/A". Anything not in this formula (such as mass, colour, or shape of coiling) is not a direct factor. The usual factors to list are length, cross-sectional area, material, and temperature.