Question

Why is Tungsten metal not used as a Thermionic emitter? How is it modified to be a good Thermion emitter?

• A. i) because it has high work function ii) by coating with a substance with high work-function
• B. i) because it has low work function ii) by coating with a substance with low work-function
• C. i) because it has high work function ii) by coating with a substance with low work-function
• D. i) because it has low work function ii) by coating with a substance with high work-function
• E. i) because it has very high work function ii) by coating with a substance with high melting point

Answer 1

The correct option is C

i) because it has high work function ii) by coating with a substance with low work-function

election-volt and 1eV = 1.6 x 10^-19J