Q 12-12-100JEE MainJEE Main 2021 (26 Aug, Shift 1)Easy
A particular hydrogen like ion emits radiation of frequency $2.92\times10^{15}$ Hz when it makes transition from $n = 3$ to $n = 1$. The frequency in Hz of radiation emitted in transition from $n = 2$ to $n = 1$ will be:
Answer: (B) $2.46\times10^{15}$
$f \propto \left(\dfrac{1}{n_1^2} - \dfrac{1}{n_2^2}\right)$:
$$\frac{f_{2\to1}}{f_{3\to1}} = \frac{1 - \frac{1}{4}}{1 - \frac{1}{9}} = \frac{3/4}{8/9} = \frac{27}{32}$$
$f_{2\to1} = 2.92\times10^{15}\times\dfrac{27}{32} \approx 2.46\times10^{15}$ Hz.
Solution by Sreeraj P, M.Sc Physics