“To emit a free electron from a metal surface a minimum amount of energy must be supplied”.
1. It is called…….
2. Give three method to supply energy to a free electron
3. For metal A (tungsten) – work function is 4.52 eV for metal B (thoriated tungsten) it is 2.6 ev, for metallic (oxide coated tungsten) it is 1 eV. Which will you prefer as a good electron emitter and why?
