Question

van Vleck's derived the equation by taking in account, which
following effects on application of magnetic field:
1) Magnetic dipole tend to get aligned along the field direction
2) Distortion of orbitals takes place​

Answer 1

The correct answer to this question is option 1) Magnetic dipole tends to get aligned along the field direction.

Explanation:

• Van Vleck paramagnetism suggests a positive and temperature-independent influence on the magnetic susceptibility of an object, derived from subsequent corrections to the Zeeman interaction.

• The magnetization of an object under an external small magnetic field H is approximately explained by ,

                                           $M=XH$

• where X is the magnetic susceptibility.  

• When a magnetic field is directed to a paramagnetic material, its magnetization is parallel to the field and X > 0.  

• For a diamagnetic material, the magnetization dissents the field, and X < 0.