Q. If $R$ is the Rydberg’s constant for hydrogen the wave number of the first line in the Lyman series will be
A) $\frac{R}{4}$
B) $\frac{3R}{4}$
C) $\frac{R}{2}$
D) $2R$
Explanation
(b) For Lyman series
$\overline{v} = \frac{1}{\lambda} = R\left( \frac{1}{1^{2}} - \frac{1}{n^{2}} \right)$ here $n = 2,\ 3,\ 4,\ 5\ldots.$
For first time $\overline{v} = R\left( \frac{1}{1^{2}} - \frac{1}{2^{2}} \right) \Rightarrow \overline{v} = R\left( 1 - \frac{1}{4} \right) = \frac{3R}{4}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.