What would be maximum wavelength for Brackett series of hydrogen-spectrum?
What would be maximum wavelength for Brackett series of hydrogen-spectrum?
- $74583 Å$
- $22790 Å$
- $40519 Å$
- $18753 Å$
Solution
For Brackett series, $n_1=4, n_2=5,6,7 \ldots \ldots \ldots$ $\frac{1}{\lambda}=R\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)$
where $R=1.09678 \times 10^7 \mathrm{~m}^{-1}$, called Rydberg's constant.
$\frac{1}{\lambda}=R\left(\frac{1}{4^2}-\frac{1}{n_2^2}\right)$
For maximum wavelength, $n_2=5$
$\begin{aligned}
& \frac{1}{\lambda_{\max }}=1.09687 \times 10^7\left(\frac{1}{4^2}-\frac{1}{5^2}\right) \\
& \lambda_{\max }=40519 Å
\end{aligned}$
.
Asked in: NEET 2012 (Mains)
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