If $\lambda_1$ and $\lambda_2$ are the wavelengths of the first member of the Balmer and Paschen series in a hydrogen atom,respectively,then the ratio of the respective frequencies,$f_1 / f_2$,is:

Which series of the hydrogen spectrum was observed first?

The frequencies for the series limit of the Balmer and Paschen series are $f_1$ and $f_3$,respectively. If the frequency of the first line of the Balmer series is $f_2$,then the relation between $f_1, f_2$,and $f_3$ is:

The stopping potential for the photoelectrons emitted from a metal surface of work function $1.7 \ eV$ is $10.4 \ V$. Identify the energy levels corresponding to the transitions in a hydrogen atom which will result in the emission of a wavelength equal to that of the incident radiation for the above photoelectric effect.

The ratio of the largest to shortest wavelengths in the Lyman series of hydrogen spectra is

What is the maximum wavelength of the $H_{\alpha}$ line in the Balmer series of the hydrogen atom (in $nm$)?