Layman series describe the ultraviolet emission lines that the hydrogen atom emits when an electron is moved from a higher energy level to level 1.
For n = 2
The wavelength = 121.5 nm
velocity = wavelength * frequency
frequency = velocity / wavelength
frequency = (3 * 10^8) / (121.5 * 10^9) = 2.469 * 10^15 Hz
