Question

A piece of copper and another of $Ge$ are cooled from room temperature to $80K$. The resistance of:

• A. Each of them increases
• B. $Cu$ increases and that of $Ge$ decreases
• C. $Cu$ decreases and that of $Ge$ increases
• D. Each of them decreases

Answer 1

The correct option is C $Cu$ decreases and that of $Ge$ increases

Resistance of $Cu$ decreases with the decrease in temperature (because it is a metal i.e., a conductor) but resistance of $Ge$ increases with the decrease of temperature (because $Ge$ is a semiconductor).