Question

A photons of energy $10.2eV$ collides inelastically with a stationary hydrogen atom (in ground state). After few micro-second another photon of energy $15.0eV$ collides with same hydrogen atom. Which of the following can be detected by a suitable detector?

• A. One photon of $10.2eV$ and electron of energy $1.4eV$
• B. One photon of $3.4eV$ and electron of energy $10.2eV$
• C. Two photon of energy $10.2eV$
• D. Two photon of energy $3.4eV$

Answer 1

The correct option is A One photon of $10.2eV$ and electron of energy $1.4eV$

The electron in the ground state $\Rightarrow 13.6eV$

second level energy $=3.4eV$

When the first photon collides with $10.2eV$ energy. It will take the $e^{-}$ to $10.2eV$ to the first excited state but the $H-$atom $\Rightarrow$ thus $10.2eV$ is energy.

The energy required to eject electron $(15.0-13.6)=1.4eV$