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When the temperature of a conductor increases, the ratio of its conductivity to its resistivity ______.

Asked in GUJCET 2018 · Temperature dependence of resistance

Answer: (3) decreases

Step-by-step solution

Idea: conductivity and resistivity are reciprocals, σ=1/ρ.

So σ/ρ=1/(ρ²).

In a metal, heating makes the ions vibrate more, collisions become more frequent, the relaxation time falls and ρ increases.

As ρ increases, 1/(ρ²) decreases.

So the ratio decreases.

Why the other options are wrong

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