Question

A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of

• A. Each of these increases
• B. Each of these decreases
• C. Copper strip increases and that of germanium decreases
• D. Copper strip decreases and that of germanium increases

Answer 1

The correct option is D Copper strip decreases and that of germanium increases

Copper is a conductor while germanium is a semiconductor.
In case of conductor resistance decreases with temperature while in case of semi-conductor resistance increases with temperature. Hence the resistance of copper strip decreases and that of germanium increases.