Question

The wavelength of the first line of Balmer series is $6563\mathring{A}$. The Rydberg's constant is

• A. $1.09\times {10}^5{m}^{-1}$
• B. $1.09\times {10}^6{m}^{-1}$
• C. $1.097\times {10}^7{m}^{-1}$
• D. $1.09\times {10}^8{m}^{-1}$

Answer 1

The correct option is C $1.097\times {10}^7{m}^{-1}$

For Balmer series: $n_1=2$

First line: $n_2=3$
Putting in formula shown in the figure:
$\frac{1}{\lambda }=R(\frac{1}{2^2}-\frac{1}{3^2})=\frac{5R}{36}$
$\frac{36}{5R}=6563\times {10}^{-12}m$
$R=1.097\times {10}^7{m}^{-1}$