Obtain an expression for the frequency of radiation emitted when a hydrogen atom de-exites from level n to level (n-1) . For large n, show that frequency equals the classical frequency of revolution of the electron in the orbit.

Explanation

The energy of an electron in the n -th energy level of hydrogen atom
`E_n =(-2pi^2me^4)/((4pi in_0)^2*n^2h^2)`
`therefore E_n-E_(n-1)=(2pi^2me^4)/((4piin_0)^2*h^2)*(2n-1)/(n^2(n-1)^2)`
`therefore` Frequency, f `=(E_n-E_(n-1))/(h) =(2pi^2me^4)/((4piin_0)^2h^3) *(2n-1)/(n^2(n-1)^2)`