Question

The wavelength of the first line of Balmer series is $6563\mspace{6mu} Å$. The Rydberg constant for hydrogen is about.

• A. $1.09 \times 10^{7}per\mspace{6mu} m$
• B. $1.09 \times 10^{8}per\mspace{6mu} m$
• C. $1.09 \times 10^{9}per\mspace{6mu} m$
• D. $1.09 \times 10^{5}per\mspace{6mu} m$

Answer 1

Answer: (A)

$1.09 \times 10^{7}per\mspace{6mu} m$

Answer 2

$\frac{1}{\lambda} = R\left\lbrack \frac{1}{4} - \frac{1}{9} \right\rbrack = \frac{5R}{36}$

$\therefore R = \frac{36}{5\lambda} = \frac{36}{5 \times 6563 \times 10^{- 10}} = 1.09 \times 10^{7}m^{- 1}$