Sir , could u plse explain the ZEEMAN EFFECT,

and how does it differentiates between orbitals

When an external magnetic field is applied, sharp spectral lines like the n=3 to 2 transition of hydrogen split into multiple closely spaced lines. First observed by Pieter Zeeman, this splitting is attributed to the interaction between the magnetic field and the magnetic dipole moment associated with the orbital angular momentum. In the absence of the magnetic field, say the hydrogen energies depend only upon the principal quantum number n, and the emissions occur at a single wavelength.

 

An external magnetic field will exert a torque on a magnetic dipole and the magnetic potential energy which results in

 

 

The magnetic dipole moment associated with the orbital angular momentum is given by

For magnetic field in the z-direction this gives

Considering the quantization of angular momentum, this gives equally spaced energy levels displaced from the zero field level by

This displacement of the energy levels gives the uniformly spaced multiplet splitting of the spectral lines which is called the Zeeman effect.

 

The magnetic field also interacts with the electron spin magnetic moment, so it contributes to the Zeeman effect in many cases. The electron spin had not been discovered at the time of Zeeman's original experiments, so the cases where it contributed were considered to be anomalous. The term "anomalous Zeeman effect" has persisted for the cases where spin contributes. In general, both orbital and spin moments are involved, and the Zeeman interaction takes the form

The factor of two multiplying the electron spin angular momentum comes from the fact that it is twice as effective in producing magnetic moment. This factor is called the spin g-factor or gyromagnetic ratio.

 

The above treatment of the Zeeman effect describes the phenomenon when the magnetic fields are small enough that the orbital and spin angular momenta can be considered to be coupled. For extremely strong magnetic fields this coupling is broken and another approach must be taken. The strong field effect is called the Paschen-Back effect.

Dear rajat,

don't you worry at all as Zeeman and Paschen effect kind of things are not there in the syllabus, but I have explained just for some inquisitive minds and those who are willing to go beyond the syllabus for the sake of their interests.