Question

If the series limit frequency of the Lyman series is $v_L$, then the series limit frequency of the P fund series is?

• A. $v_L/16$
• B. $v_L/25$
• C. $25v_L$
• D. $16v_L$

Answer 1

The correct option is B $v_L/25$

given that $\overline{\nu }=R[\frac{1}{n_1^2}-\frac{1}{n_2^2}]$

for lyman wave number $\overline{\nu }=\frac{1}{\lambda }$

so $\nu =RC[\frac{1}{n_1^2}-\frac{1}{n_2^2}]$

$\nu =RC[\frac{1}{1^2}-\frac{1}{\infty }]$

so ${\nu }_l=RC$

for Pfund ${\nu }_p=RC[\frac{1}{5^2}-\frac{1}{\infty }]$ $=\frac{RC}{25}=\frac{{\nu }_l}{25}$

so option B is correct.