Q. Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1eV. The spectral lines emitted by hydrogen atoms according to Bohr’s theory will be
A) One
B) Two
C) Three
D) Four
Explanation
(c) Energy in excited state $= - 13.6 + 12.1 = - 1.5\ eV$
$\therefore\ \frac{- 13.6}{n^{2}} = - 1.5$
$\therefore\ n = \sqrt{\frac{13.6}{1.5}} = 3$
Number of spectral lines
$= \frac{n(n - 1)}{2} = \frac{3(3 - 1)}{2} = 3$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.