JEE Main levelSingle correct optionDifficulty 2 of 3ss206
On increasing temperature from 300 K to 400 K, the electrical conductivity of copper and of pure silicon changes as
Aboth increase
Bcopper decreases, silicon increases
Ccopper increases, silicon decreases
Dboth decrease
Answer: B
In a metal, hotter lattice vibrations scatter electrons more, so conductivity falls. In a semiconductor more electrons are thermally excited across the band gap, so conductivity rises.