A piece of copper and a piece of germanium are cooled from room temperature 20 °C down to 80 K. The resistance of
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → copper decreases and that of germanium increases.
Copper is a metal, and germanium is a semiconductor.
For metals:
→ As temperature decreases, the vibration of lattice ions reduces, causing resistance to decrease.
For semiconductors:
→ As temperature decreases, the number of thermally generated charge carriers decreases, causing resistance to increase.
∴ Correct answer: Copper decreases and that of germanium increases.