Question

A piece of copper and another of germanium are cooled from room temperature to 77 K. what will impact on the resistance of each of them?

(a) Each of these decreases

(b) Copper strip increases and that of germanium decreases

(c) Copper strip decreases and that of germanium increases

(d) Each of these increases

This question was posed to me at a job interview.

My query is from Classification of Metals, Conductors and Semiconductors topic in section Semiconductor Electronics : Materials, Devices and Simple Circuits of Physics – Class 12

Answer 1

The correct choice is (c) Copper strip decreases and that of germanium increases

To explain I would say: With the decrease of temperature, the resistance of copper, which is a metallic conductor, will decrease, whereas the resistance of germanium, which is a semiconductor will increase.