Question

The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is :

• A. 1
• B. 4
• C. 0.5
• D. 2

Answer 1

Answer: (B)

4

Answer 2

For last Balmer series
$\frac{1}{\lambda_{b}}=R\left[\frac{1}{2^{2}}-\frac{1}{\infty^{2}}\right]$
$\lambda_{b}=\frac{4}{R}$
For last Lyman series
$\frac{1}{\lambda_{l}}=R\left[\frac{1}{1^{2}}-\frac{1}{\infty^{2}}\right]$
$\lambda_{I}=\frac{1}{R}$
$\frac{\lambda_{b}}{\lambda_{l}}=\frac{\frac{4}{R}}{\frac{1}{R}}$
$\frac{\lambda_{b}}{\lambda_{l}}=4$