Question

The maximum wavelength of Lyman series is

• A. $\frac{4}{3R}$
• B. $\frac{1}{R^2}$
• C. $\frac{C}{R}$
• D. $\frac{1}{RC}$

Answer 1

The correct option is A $\frac{4}{3R}$

According to Rydberg's formula:
$\frac{1}{\lambda }=R[\frac{1}{n_1^2}-\frac{1}{n_2^2}]$ For Lyman $\Rightarrow n_1=1$
From the above equation, we easily see that photon with maximum wavelength for Lyman is ejected only when a transition occurs just from next highest orbit i.e., $n_2=2$
So, $\frac{1}{\lambda }=R[1-\frac{1}{4}]$
$\Rightarrow \lambda =\frac{4}{3R}$