Question

Ratio of longest wavelengths corresponding to Lyman and Balmer series in hydrogen spectrum is

• A. $\frac{5}{27}$
• B. $\frac{3}{23}$
• C. $\frac{7}{29}$
• D. $\frac{9}{31}$

Answer 1

Answer: (A)

$\frac{5}{27}$

${\lambda }_L=\frac{1}{R(1-\frac{1}{4})}=\frac{4}{3R}$

${\lambda }_B=\frac{1}{R(\frac{1}{4}-\frac{1}{9})}=\frac{1}{R\left(\frac{5}{36}\right)}=\frac{36}{5R}$

$\frac{{\lambda }_L}{{\lambda }_B}=\frac{4}{3R}\times \frac{5R}{36}$$=\frac{5}{27}$