Question

Calculate the wavelength of the spectral line, when an electron in the hydrogen atom undergoes a transition from the energy level 4 to energy level 2.
$R_H=109678c{m}^{-1}$

• A. 486 nm
• B. 554 nm
• C. 386 nm
• D. 427 nm

Answer 1

The correct option is A 486 nm

Using the formula,
$\frac{1}{\lambda }=R_H(\frac{1}{n_1^2}-\frac{1}{n_2^2})\text{where}\lambda \text{is the wavelength}$
$R_H=109678c{m}^{-1};n_1=2;n_2=4\frac{1}{\lambda }=109678[\frac{1}{4}-\frac{1}{16}]=109678\times \frac{3}{16}$
On solving, $\lambda =486$ nm