Calculate the wavenumber of a photon emitted during the transition from the orbit of $n=3$ to $n=2$ in a hydrogen atom. $(R_{H} = 109677 \ cm^{-1})$ (in $cm^{-1}$)

The wavelength and frequency of a photon with energy $2 \ eV$ are respectively:

When an electric discharge is passed through hydrogen gas,the hydrogen molecules dissociate to produce excited hydrogen atoms. These excited atoms emit electromagnetic radiation of discrete frequencies which can be given by the general formula
$\bar{v} = 109677 \left[ \frac{1}{n_{i}^{2}} - \frac{1}{n_{f}^{2}} \right] \ cm^{-1}$
What points of Bohr's model of an atom can be used to arrive at this formula? Based on these points,derive the above formula,giving a description of each step and each term.

If an atom has $x$ energy levels,what will be the total number of spectral lines in its emission spectrum?

If the wavelength of light is $5.89 \times 10^{-5} \ cm$,then the energy of one photon in the given light will be ......

What is the potential energy of the electron in the $L$ shell of the hydrogen atom? (in $eV$)