Measurement of Susceptibility of Paramagnetic solution Quinck’s tube method

The measurement of susceptibility of a paramagnetic solution by Quinck’s tube method involves determining how easily a solution becomes magnetized when exposed to a magnetic field, using a special U-shaped tube apparatus.

Principle and Setup

Quinck’s tube method is based on the force experienced by a magnetized liquid in a non-uniform magnetic field. The apparatus consists of a U-shaped Quincke's tube with one narrow and one wide limb. The paramagnetic solution is filled into the tube, which is then placed so that the narrow limb sits between the poles of an electromagnet. The magnetic field strength is measured using a digital Gauss meter, and the rise in liquid level in the narrow limb is measured with a traveling microscope when the magnetic field is applied.

Procedure

When the paramagnetic liquid in the narrow limb is exposed to the magnetic field, it rises due to the induced magnetic moment. The height difference (

h

h) between the two liquid levels (before and after applying the field) is recorded. This change corresponds to the force exerted by the magnetic field and is proportional to the material’s susceptibility.

Calculation of Susceptibility

The magnetic susceptibility (

χ

χ) can be calculated using the following formula:

χ

=

2

(

ρ

−

σ

)

g

h

H

2

χ=

H

2

2(ρ−σ)gh

where

ρ

ρ = density of liquid or solution

σ

σ = density of air

g

g = acceleration due to gravity

h

h = height difference observed in the narrow limb

H

H = applied magnetic field intensity.

The susceptibility indicates how much the solution is magnetized under the applied field, and plotting

h

h versus

H

2

H

2

(or field squared) allows direct determination from the slope.

Applications

This method is commonly used for measuring the susceptibility of paramagnetic solutions such as manganese sulfate in educational and research laboratories.

This description provides the essential principles, apparatus, procedure, and formula associated with the Quinck's tube method for measuring the susceptibility of paramagnetic solutions.