Question

The wave number of the $H_{\beta }$ - line in Balmer series of hydrogen spectrum is:

• A. $\frac{5R}{36}$
• B. $\frac{3R}{16}$
• C. $\frac{21R}{100}$
• D. $\frac{3R}{4}$

Answer 1

The correct option is B $\frac{3R}{16}$

$H_{\beta }$ line of balmer series corresponds to the transition from $n=4$ to $n=2$ level.

Using $\frac{1}{\lambda }=R[\frac{1}{2^2}-\frac{1}{n^2}]$, the corresponding wavelength for $H_{\beta }$ line is,

$\frac{1}{\lambda }=R[\frac{1}{2^2}-\frac{1}{4^2}]$

$\lambda =\frac{3R}{16}$