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MHT CET · Physics · Atomic Physics

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. A \(\frac{7}{5}\)
  2. B \(\frac{27}{20}\)
  3. C \(\frac{27}{5}\)
  4. D \(\frac{20}{7}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{20}{7}\)

Step-by-step Solution

Detailed explanation

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