JEE Advanced · 2007 · 08 Apr 2007 · Paper 1 · Modern Physics

The largest wavelength in the UV region (Lyman series) corresponds to the transition from $n=2$ to $n=1$, which is 122 nm.

The smallest wavelength in the infrared region (Paschen series) corresponds to the transition from $n=\infty$ to $n=3$.

Using the Rydberg formula:



For the Lyman series ($n=2$ to $n=1$):



For the Paschen series ($n=\infty$ to $n=3$):



Dividing these: