Electron in Hydrogen atom first jumps from third excited state to second excited state and then from second…

Electron in Hydrogen atom first jumps from third excited state to second excited state and then from second excited state to first excited state. The ratio of the wavelengths $\lambda_{1}: \lambda_{2}$ emitted in the two cases respectively is
  1. $\frac{7}{5}$
  2. $\frac{27}{20}$
  3. $\frac{27}{5}$
  4. $\frac{20}{7}$

Solution

$\frac{1}{\lambda_{1}}=\mathrm{R}\left(\frac{1}{2^{2}}-\frac{1}{3^{2}}\right)=\mathrm{R}\left(\frac{1}{4}-\frac{1}{9}\right)=\mathrm{R}\left(\frac{5}{36}\right)$ $\frac{1}{\lambda_{2}}=\mathrm{R}\left(1-\frac{1}{2^{2}}\right)=\mathrm{R}\left(\frac{3}{4}\right)$ $\frac{\lambda_{1}}{\lambda_{2}}=\frac{3}{4} \times \frac{36}{5}=\frac{27}{5}$

Asked in: MHT CET 2020 (12 Oct Shift 1)

Practice more Atomic Physics questions on Aicharya