Q. The ionization potential of hydrogen atom is $- 13.6\ eV$. An electron in the ground state of a hydrogen atom absorbs a photon of energy $12.75eV$. How many different spectral lines can one expect when the electron make a downward transition

A) 1
B) 4
C) 2
D) 6
Explanation

(d) $E = E_{1}/n^{2}$
[image:13_image31.emf]
Energy used for excitation is $12.75\ eV$
$i.e.,( - 13.6 + 12.75)eV = - 0.85\ eV$
The photons of energy $12.75\ eV$ can excite the fourth level of $H$-atom. Therefore six lines will be emitted $\left( n\frac{(n - 1)}{2}lines \right)$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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