Q. 23

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

Answer :

corresponds to Balmer series transition from n=5 to n=2. Now the electron of ground state requires energy for moving to 5^{th} orbit from 1^{st} orbit.

Energy at n=1,

Energy at n=5,

∴ energy required =

Now if the momentum is conserved, we know that, angular momentum for electron in n^{th} orbit is given as,

Initial momentum = final momentum

Momentum of electron in 5^{th} orbit

= Momentum of electron in 2^{nd} orbit+ momentum of photon

∴ the momentum of the photon released =

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