Calcuate `n(T)//n (1000 K)` for tungsten emitter at `T = 300 K, 2000 K and 3000 K` where `n(T)` represent the number of thermions emitted per secodn by the surface at temperature. `T`. Work function of tungsten is `4.52 eV`.

Explanation

Since ` i=ne or n=i/e `
'e' is same in all cases.
` We know, i= AST^2 e^(-phi/RT),`
` phi = 4.52 e.V, `
` K = 1.38 xx (10^-23)J/K.`
` n(1000) = As xx (1000)^2 `
` x e^(-4.52 xx 1.6 xx (10^-19)//1.38 xx (10^-23) xx 1000)`
` = (10^6) xx 1.7396 xx (10^-23) `
` = 1.7396 xx (10^-17)`
` T = 300K ` .
(a) `n(T)/n(100K) =`
`((As xx (300^2) xx e^(-4.52 xx 1.6 xx (10^-19)//1.38 xx (10^-23) xx 1000))/ (As xx 1.7396 xx (10^-17)))`
` = 1.340 xx (10^16) ` .