Question

A photon collides with a stationary hydrogen atom in ground state, inelastically. The energy of the colliding photon is $10.2\text{eV}$. Almost instantaneously, another photon collides with the same hydrogen atom inelastically, with an energy of $15\text{eV}$. What will be observed by the detector?

• A. One photon of energy $10.2\text{eV}$ and one electron of energy $1.4\text{eV}$
• B. One electron having kinetic energy nearly $11.6\text{eV}$
• C. Two photons of energy $1.4\text{eV}$
• D. Two photons of energy $10.2\text{eV}$

Answer 1

The correct option is B One electron having kinetic energy nearly $11.6\text{eV}$

The total energy of the incident photons is,

$E_{in}=10.2+15=25.2\text{eV}$

Energy required to remove an electron from the ground state of H-atom is $E_{ioni}=13.6\text{eV}$

The remaining energy of the photon, imparted as kinetic Energy to the electron. i.e.,

$K{E}_e=E_{in}-13.6$

$=25.2-13.6$

$=11.6\text{eV}$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(B\right)$ is the correct answer.