Breadth of spectral line:- The Breadth of spectral line is defined as the Frequency separation blo turo points A&B Whope intensities are 2012 frequeny (2) half that of the maximum intensity. Here breadth of spectral line is given by- AV = 22-29 There are mainly for Causes of broadning of spectral lines→ (1) Natural Broadning (2) Doppler effect. 3) external effects:- Collision broadning Pressure broadsning Stork effect (&plitting of spectral Line in the electric field.) The spectral lines arise due to electrons, transition blw two energy level. According to .m. the energy levels of an atom are not discrete, but they have a finite energy breadth (AE). In which The probability distribution is concentrated in regions where the terms are observed. According to Heisenberg Uncertainty principle, (I) Where DE y energy spread of a state. At y time for which atom remains in that State. ΔΕ = hav fromegn (2), we have. (2) (2.) Doppler Broadning:- Let the frequency (Natural) of the source of spectral line is Yo Let the source is moving with velocity u related to relative to the observer. Then The measured frequency (2) is given by In Case of gaseous discharge (such ax a discharge lamp), the center of mase of the Source is fixed, but the atoms emitting the light have velocities owe to thermal agitation The random motion of the atoms of the gay produce a net broading of the special line, with no apparent displacement of 106 centor of mass. This means that the Spectral line Consists of a range of frequencies disposed about the natural frequency vo According to maxwell-Boltzman distribution of velocities, the probability that the velocity of an atom of an ideal gas lier blw V & (v+dv) is 31