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JEE Main 2019 (12 Apr, Shift 2) · Transitions, Photon Emission & Excitation

Transitions, Photon Emission & Excitation question from JEE Main 2019 (12 Apr, Shift 2)

Q54JEE Main 2019 · 12 APR · SHIFT 2Medium

Transitions, Photon Emission & Excitation

The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to the first excited state. The ratio of the respective wavelengths, λ1λ2\frac{\lambda_{1}}{\lambda_{2}}, of the photons emitted in this process is:

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Answer: (d)

  1. Third excited n=4n=4, second excited n=3n=3, first excited 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)=20R144\frac{1}{\lambda_2} = R\left(\frac{1}{4} - \frac{1}{9}\right) = \frac{20R}{144}
  4. λ1λ2=207\frac{\lambda_1}{\lambda_2} = \frac{20}{7}, so the answer is (d).
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