Question

The rate of emission of thermions is the surface area of surface emitting thermions.

• A. independent of
• B. inversely proportional to
• C. directly proportional to
• D. None of these

Answer 1

The correct option is C directly proportional to

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. More is the surface area of the metal, more the charge carriers overcome the work function which results in the increase in the rate of emission of thermions. Hence rate of emission of thermions is directly proportional to the surface area of the surface emitting thermions.