Question

Why are metals with low work function preferred as thermionic emitters?

• A. They emit thermions at low temperature.
• B. They emit thermions at high temperature.
• C. They emit thermions at room temperature.
• D. None of these

Answer 1

The correct option is A They emit thermions at low temperature.

Thermal energy given to the charge carriers overcome the work function of the metal surface and thus flow of charge carriers takes place from the metal surface. Lower the work function of the metal, more easily will be the thermions emitted. Metals with low work function emit thermions at low temperature. Hence the metal with low work functions are preferred as thermionic emitters.