Q.

An electron in a hydrogen atom undergoes a transition from an orbit with quantum number ni to another with quantum number nf. Vi and Vf are respectively the initial and final potential energies of the electron. If ViVf=6.25, then the smallest possible nf is                    [2017]


Ans.

(5)

Here,  ViVf=-27.2nf2-27.2ni2=nf2ni2=6.25

∴ nfni=2.5=52

∴  Smallest possible nf=5