Question

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

• A. each of them increases
• B. each of them decreases
• C. copper increases and germanium decreases
• D. copper decreases and germanium increases

Answer 1

Answer: (D)

copper decreases and germanium increases

We know, a piece of copper is a metal while that of germanium is a semiconducting material. For metals resistance increases with increase in temperature. The semiconductor has a negative temperature coefficient of resistance. Hence, when it is cooled its resistance increases.