Q.

A light of energy 12.75 eV is incident on a hydrogen atom in its ground state. The atom absorbs the radiation and reaches to one of its excited states. The angular momentum of the atom in the excited state is xπ×10-17 eV s. The value of x is _________

(use  h=4.14×10-15 eVs, c=3×108 ms-1)                  [2023]


Ans.

(828)

In the ground state energy=-13.6 eV

So energy  -13.6 eVn2=-13.6+12.75

           -13.6 eVn2=-0.85

           n=16=4

Angular momentum=nh2π=4h2π=2hπ

Angular momentum=2π×4.14×10-15=828×10-17πeVs