Question

Calculate the maximum wavelength of Balmer series in the hydrogen spectrum. Calculate the corresponding wave number.
$R=1.097\times {10}^7{m}^{-1}$

Answer 1

Maximum wavelength means minimum energy.

$\therefore$ $\frac{1}{\lambda }={Rz}^2(\frac{1}{n_1^2}-\frac{1}{n_2^2})$

$=1.097\times {10}^7\times 1(\frac{1}{4}-\frac{1}{9})$

$\frac{1}{\lambda }=1.097\times {10}^7\times \frac{5}{36}$

$\lambda =6.56\times {10}^{-7}m$

$\frac{1}{\lambda }=$ wave number $=0.152\times {10}^7{m}^{-1}$