Previous Year Question

The resistance of a uniform conductor is expressed by the relation:

R = ρL/A

where R = resistance, ρ = resistivity of the material, L = length of the conductor and A = cross-sectional area. Thus, resistance is directly proportional to the length and inversely proportional to the cross-sectional area. The resistivity ρ depends on the nature of the material.

For an ordinary solid conductor, humidity is not a factor appearing in this basic relation for determining resistance. Therefore, among the given options, humidity of the conductor is the correct answer.

Important fact: Resistivity depends on temperature; therefore, the resistance of a conductor can change when its temperature
changes.