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NEET 2012 (AIPMT, Prelims) · Transitions, Photon Emission & Excitation

Transitions, Photon Emission & Excitation question from NEET 2012 (AIPMT, Prelims)

Q69NEET 2012 · AIPMT · PRELIMSMedium

Transitions, Photon Emission & Excitation

Electron in hydrogen atom first jumps from third excited state to second excited state and then from second excited to the first excited state. The ratio of the wavelengths λ\lambda1: λ\lambda2 emitted in the two cases is

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Answer: (d)

  1. Third excited state is n=4n=4, second excited is n=3n=3, first excited is n=2n=2.
  2. 1λ1=R(19−116)=7R144\frac{1}{\lambda_1} = R\left(\frac{1}{9} - \frac{1}{16}\right) = \frac{7R}{144}
  3. 1λ2=R(14−19)=5R36=20R144\frac{1}{\lambda_2} = R\left(\frac{1}{4} - \frac{1}{9}\right) = \frac{5R}{36} = \frac{20R}{144}
  4. λ1λ2=207\frac{\lambda_1}{\lambda_2} = \frac{20}{7}, so the answer is (d).
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