A hypothetical atom has two energy levels, with a transition wavelength between them of 580 nm. In a particular sample at 300 K, `4.0xx10^(20)` such atoms are in the state of lower energy. (a) How many atoms are in the upper state, assuming conditions of thermal equilibrium? (b) Suppose, instead, that `3.0xx10^(20)` of these atoms are ''pumped'' into the upper state by an external process, with `1.0xx10^(20)` atoms remaining in the lower state.

Explanation

(a) `5.0xx10^(-16)ltlt1`, so no electron, (b) 68 J