What is paramagnetic susceptibility ? Describe one method of its determination.

Magnetic susceptibility means how much attracted or repelled when substance placed in an external magnetic field. It helps to measure material magnetization.

Paramagnetic susceptibility is a tendency to attract in the magnetic field. Or align the dipole moment of substances in the direction of the magnetic field.

Determination:-
Gouy method is one of the best methods of determining magnetic susceptibility,

The determination magnetic susceptibility totally depends on the measurement of  B/H from the classical magnetism
Lenz's law can be stated as
                                            B/H= 1+4πK
Where B/H is the magnetic permeability of the material and K is the magnetic susceptibility per unit volume.

The Gouy's method includes the measurement of force on the sample by the externally applied magnetic field and depends upon the tendency of the sample to align itself in high or low magnetic field strength. The force at any given point of the sample (say dx) is given by:

𝑑𝐹 = µ°𝐻 𝐾𝑑𝑉  .dH/𝑑𝑥

Where μ° symbolizes the permeability of the vacuum (value is 1 when using c.g.s. system of units), dV is the volume of the sample at point dx, H is the magnitude of the magnetic field at point dx and K represents the magnetic susceptibility per unit volume. The Gouy tube, packed uniformly with the sample is placed in the magnetic field such that each end of the glass tube experiences a constant field strength. In order to achieve this situation, the Gouy’s tube must be packed to a certain height like 10 or 15 cm, and the tube is then hanged between the electromagnetic poles in such a way that the bottom of the sample lies in the center of the magnetic field (an area where a uniform field strength can be easily achieved); while the top of the sample is out of the field (H = 0).