Question

When a pure semiconductor is heated, its resistance

• A. Goes down.
• B. Goes up.
• C. Remains the same.
• D. None of the these.

Answer 1

The correct option is A

Goes down.

When the temperature is raised, some of the covalent bonds in the semiconductor break due to the thermal energy supplied. The breaking of the bond set those electrons free which are engaged in the formation of these bonds. These free electrons can constitute a tiny electric current if potential difference is applied across the semiconductor. Hence the resistance decreases with the rise in temperature.