Explain the different types of spectral series.

(i) Lyman series. The lyman series is obtained when electrons jump to first orbit (n₁ = 1) from outer orbits (n₂ = 2, 3, 5.....). Therefore, the formula for calculating the wavelengths of the lines in this series is
$\frac{1}{\mathrm{\lambda }}={\mathrm{R}}_{\mathrm{H}}\left[\frac{1}{(1{)}^2}-\frac{1}{{\mathrm{n}}_2^2}\right]\text{ where }{\mathrm{n}}_2=2,3,4\dots \dots$
This series lies in the ultraviolet region which is the invisible region.
(ii) Balmer series. The Balmer series is obtained when electrons jump to second orbit (n₁ = 2) from outer orbits (n₂ = 3, 4, 5....). Therefore, the formula for calculating the wavelength of the lines in this series is
$\frac{1}{\mathrm{\lambda }}={\mathrm{R}}_{\mathrm{H}}\left[\frac{1}{2^2}-\frac{1}{{\mathrm{n}}_2^2}\right]\text{ where }{\mathrm{n}}_2=3,4,5,\dots \dots$
This series lies in the visible spectrum and was found first of all in the hydrogen series.
(iii) Paschen series. The Paschen series is obtained when electrons jump to third orbit (n₁ = 3) from outer orbits (n₂ = 4, 5, 6......) Therefore, the formula for calculating the wavelengths of the lines in this series is
$\frac{1}{\mathrm{\lambda }}={\mathrm{R}}_{\mathrm{H}}\left[\frac{1}{3^2}-\frac{1}{{\mathrm{n}}_2^2}\right]\text{ where }{\mathrm{n}}_2=4,5,6\dots .$
This series also lies in the infrared region.
(v) Pfund series. The Pfund series is obtained when electrons jump to fifth orbit (n₁ = 5)from outer orbits (n₂ = 6, 7, 8.....). Therefore, the formula for calculating the wavelengths of the lines in this series is
$\frac{1}{\mathrm{\lambda }}={\mathrm{R}}_{\mathrm{H}}\left[\frac{1}{5^2}-\frac{1}{{\mathrm{n}}_2^2}\right]\text{ where }{\mathrm{n}}_2=6,7,8$
This series also lies in the infrared region.
The various spectral series of hydrogen atom are represented in Figs (same as in LAQ 2^nd question).