A photon collides with a stationary hydrogen atom in ground state inelastically. Energy of the colliding photon is 10.2 eV. After a time interval of the order of micro second another photon collides with same hydrogen atom inelastically with an energy of 15eV. What wil be observed by the detector?
(a) 2 photons of energy 10.2 eV
(b) 2 photons of energy 1.4 eV
(c ) One photon of energy 10.2 eV and an electron of energy 1.4 eV
(d) One photon of energy 10.2 eV and another photon of energy 1.4 eV

Options

A. one photon of `10.2eV` and an electron of energy `1.4eV`
B. `2` photons of energy `10.2eV`
C. `2` photon of energy `3.4eV`
D. 1 photon of `3.4eV` and one electron of `1.4eV`

Answer

A

Explanation

`10.2eV` photon will be absorbed completely for transition of electron from `n=1` to `n=2` and it will be emitted back when electron is dexcited. `15eV` photon will knockout K-shell electron by absorbing `13.6eV` and `1.4eV` and rest `1.4eV` appears as its `KE`.