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Question: Answered & Verified by Expert
If an electron in hydrogen atom jumps from an orbit of level \( n=3 \) to an orbit of level \( n=2 \). the
emitted radiation has a frequency ( \( R= \) Rydberg constant, \( C= \) velocity of light)
PhysicsAlternating CurrentKCETKCET 2015
Options:
  • A \( \frac{3 R C}{27} \)
  • B \( \frac{R C}{25} \)
  • C \( \frac{8 R C}{9} \)
  • D \( \frac{5 R C}{36} \)
Solution:
2983 Upvotes Verified Answer
The correct answer is: \( \frac{5 R C}{36} \)
We know that
\[
\begin{array}{l}
\frac{1}{\lambda}=R\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right) \\
\text { Using } \lambda f=c \Rightarrow \frac{1}{\lambda}=\frac{f}{c} \\
\frac{f}{c}=R\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right) \Rightarrow f=R c\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right) \\
\text { Given } n_{1}=2 ; n_{2}=3 \\
\Rightarrow f=R c\left(\frac{1}{2^{2}}-\frac{1}{3^{2}}\right)=R c\left(\frac{1}{4}-\frac{1}{9}\right)=R c \frac{(9-4)}{4 \times 9}=\frac{5 R C}{36}
\end{array}
\]
Therefore, frequency of emitted radiation is \( \frac{5}{36} \mathrm{Rc} \)

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