## Physics XII Content

# Spectrical Series

When electrons moves around the nucleus in certain permitted orbit, it can jump from higher to the lower energy level with the emission of radiation. The wavelength of emitted radiation can be obtained by the expression:

Where R_{2}= Rydberg constant

n_{1}= lower energy level

n_{2} = higher energy level

On the basis of transition of electron from higher to lower energy level different spectral series can be obtained which are explained below

**Lyman series:**

If the transition of electron is to n_{1}= 1 from n_{2} = 2,3,4…. Lyman series can be obtained. The wavelength of the layman series can be obtained as:

The wavelength lies in the region of the ultraviolet.

**Balmer Series:**

If the transition of electron is to n_{1}=2 from n_{2 }= 3,4,5… balmer series is obtained. The wave length of balmer series can be obtained as

The wavelength lies in the visible region.

**Paschen series:**

If the transition of electrons is to n_{1} = 3 from n_{2} = 3,5,6 …. paschen series can be obtained. The wavelength of paschen series is given by

The wavelength lies int eh infrared region.

**Brackett series:**

If the transition of electron is to n_{1}= 4 from n_{2} = 5, 6 ,7 …. brakett series is obtaine . The wavelength of brackett series is given by

The wavelength lies in the infrared region

**Pfund series:**

If the transition of electrons is to n_{1} = 5 from n_{2} = 6 ,7,8 … pfund series is obtained . The wavelength of pfund series is given by

The wavelength lies in the infrared region