Q. The ratio of the longest to shortest wavelengths in Brackett series of hydrogen spectra is
A) $\frac{25}{9}$
B) $\frac{17}{6}$
C) $\frac{9}{5}$
D) $\frac{4}{3}$
Explanation
(a) For Bracket series $\frac{1}{\lambda_{\max}} = R\left\lbrack \frac{1}{4^{2}} - \frac{1}{5^{2}} \right\rbrack = \frac{9}{25 \times 16}R$
and $\frac{1}{\lambda_{\min}} = R\left\lbrack \frac{1}{4^{2}} - \frac{1}{\infty^{2}} \right\rbrack = \frac{R}{16} \Rightarrow \frac{\lambda_{\max}}{\lambda_{\min}} = \frac{25}{9}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.