What is the minimum energy that must be given to a H-atom in ground state so that it can emit an ${ H }*{γ }$ -line in Balmer series? If the angular momentum of the system is conserved, what would be the angular momentum of such
${ H }*{γ }$ photon?

Energy required for the transition from n = 2 to n = 5 is given by =

${ E }*{ 1 }$ -
${ E }*{ 5 }$ = 13.6 - 0.54 = 13.06 eV

Since, angular momentum is conserved.

Angular momentum corresponding to ${ H }

*{ γ }$ photon = Change in angular momentum of electron*

= ${ L }{ 5 }$ -

= ${ L }

${ L }_{ 2 }$ = 5h - 2h = 3h =

3 x 1.06 x ${{10}^{-34}}$ =

3.18 x ${{10}^{-34}}$ kg-${{m}^{2}}$/sec