Question

The resistance in one of the following decreases with rise in temperature. The one is

• A. Germanium
• B. Copper
• C. Gold
• D. Silver

Answer 1

The correct option is A

Germanium

1. Semi-conductors have a gap between the valence band and conductive band. Germanium is a semi-conductor
2. When a semiconductor is heated, electrons from the valence band enter the conductive band and can move freely to create the flow of current, and thus its resistance decreases.
3. Therefore, resistance decreases upon heating in Germanium.

Hence, option (A) is the correct answer.