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The ratio of maximum wavelength to minimum wavelength in Balmer series is

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For any spectral series: \[ \lambda_{\max} \Rightarrow \text{first line of the series} \] \[ \lambda_{\min} \Rightarrow \text{series limit }(n=\infty) \] For Balmer series, the lower level is always \(n=2\).
Updated On: Jun 11, 2026
  • \(\dfrac{4}{3}\)
  • \(\dfrac{3}{4}\)
  • \(\dfrac{9}{5}\)
  • \(\dfrac{5}{9}\)
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The Correct Option is C

Solution and Explanation

Concept: For the Balmer series, \[ \frac{1}{\lambda} = R \left( \frac{1}{2^2} - \frac{1}{n^2} \right), \qquad n=3,4,5,\ldots \] The maximum wavelength corresponds to the minimum energy transition and the minimum wavelength corresponds to the series limit.

Step 1:
Find the maximum wavelength. For Balmer series, the first line corresponds to \[ n=3 \rightarrow n=2 \] Hence, \[ \frac{1}{\lambda_{\max}} = R \left( \frac{1}{4} - \frac{1}{9} \right) = R \left( \frac{5}{36} \right) \] \[ \lambda_{\max} = \frac{36}{5R} \]

Step 2:
Find the minimum wavelength. The minimum wavelength occurs at the series limit, \[ n=\infty \rightarrow n=2 \] Therefore, \[ \frac{1}{\lambda_{\min}} = R \left( \frac{1}{4} - 0 \right) = \frac{R}{4} \] \[ \lambda_{\min} = \frac{4}{R} \]

Step 3:
Calculate the ratio. \[ \frac{\lambda_{\max}}{\lambda_{\min}} = \frac{\frac{36}{5R}} {\frac{4}{R}} \] \[ = \frac{36}{20} \] \[ = \frac{9}{5} \]

Step 4:
State the answer. \[ { \frac{\lambda_{\max}} {\lambda_{\min}} = \frac{9}{5} } \] Hence, the correct option is \[ {(C)} \]
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