Atoms And Nuclei

Hydrogen atom is bombarded with electrons accelerated through a potential difference of \(\mathrm{V}\), which causes excitation of hydrogen atoms. If the experiment is being performed at \(\mathrm{T}=0 \mathrm{~K}\), the minimum potential difference needed to observe any Balmer series lines in the emission spectra will be \(\frac{\alpha}{10} \mathrm{~V}\), where \(\alpha=\) __________.