Question

The energy levels of a certain atom for 1st, 2nd and 3rd levels are E, 4E/3 and 2E respectively. A photon of wavelength λ is emitted for a transition 3 → 1. What will be the wavelength of emissions for transition 2 → 1

• A. λ/3
• B. 4λ/3
• C. 3λ/4
• D. 3λ

Answer 1

Answer: (D)

3λ

Answer 2

For transition 3 → 1 $\Delta E = 2E - E = \frac{hc}{\lambda}$ ⇒ $E = \frac{hc}{\lambda}$ …..(i)

For transition 2 → 1 $\frac{4E}{3} - E = \frac{hc}{\lambda^{'}}$ ⇒ $E = \frac{3hc}{\lambda^{'}}$ …..(ii)

From equation (i) and (ii) $\lambda^{'} = 3\lambda$