Q. In a sample of hydrogen like atoms all of which are in ground state, a photon beam containing photons of various energies is passed. In absorption spectrum, five dark lines, are observed. The number of bright lines in the emission spectrum will be (assume that all transitions takes place)
A) 5
B) 10
C) 15
D) None of these
Explanation
(c) Number of lines in absorption spectrum $= (n - 1)$
$\Rightarrow 5 = n - 1 \Rightarrow n = 6$
$\therefore$ Number of bright lines in the emission spectrum
$= \frac{n(n - 1)}{2} = \frac{6(6 - 1)}{2} = 15$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.