The constant `A` in the Richordson-Dushman equation is `60 xx 10^4 A m^(-2) K^(-2)` for tungsten. A
Channel: Doubtnut
Date: 2020-07-12

The constant `A` in the Richordson-Dushman equation is `60 xx 10^4 A m^(-2) K^(-2)` for tungsten. A tungsten cathode has a total surface area of `2.0 xx 10^(-5) m^2` and operates at `2000 K`. The work function of tungsten is `4.55 eV`. Calculate the electric current due to thermionic emission.