Q 12-12-047JEE MainJEE Main 2024 (6 Apr, Shift 2)Easy
The longest wavelength associated with the Paschen series is (Given $R_H = 1.097\times10^7$ SI unit)
Answer: (B) $1.876\times10^{-6}\ \text{m}$
Longest Paschen line: $n = 4 \to 3$.
$$\frac1\lambda = R_H\left(\frac19 - \frac1{16}\right) = \frac{7R_H}{144} \Rightarrow \lambda = \frac{144}{7\times1.097\times10^7} \approx 1.876\times10^{-6}\ \text{m}$$
Solution by Sreeraj P, M.Sc Physics