13 Jul 2026

Magnetic Susceptibility of a Paramagnetic Solution by Quincke's Method

practical ug-vi magnetism susceptibility quincke

Experimental arrangement

Quincke's tube is placed between the magnet poles and the liquid-level displacement is observed as the field is changed.

Aim

To determine the magnetic susceptibility of a paramagnetic solution using Quincke’s tube method.

Apparatus

Quincke’s tube, electromagnet, travelling microscope, measuring cylinder, paramagnetic solution, and Gauss meter.

Theory

When a paramagnetic liquid is placed in a non-uniform magnetic field, its level rises in the field region. If $h$ is the rise, $H$ is the magnetic field, and $\rho$ is the density,

\[\chi=\frac{2\rho gh}{\mu_0H^2}.\]

The height difference is measured with the microscope for different values of current.

Observations

Current (A)	Field $H$ (A m$^{-1}$)	Rise $h$ (mm)
1.0	$1.20\times10^4$	1.2
1.5	$1.80\times10^4$	2.7
2.0	$2.40\times10^4$	4.8
2.5	$3.00\times10^4$	7.4

For the solution, $\rho=1050\,\text{kg m}^{-3}$.

Result

Substitution of the mean $h/H^2$ value gives

\[\boxed{\chi=3.1\times10^{-4}}.\]

Precautions

1. Remove air bubbles from the tube.
2. Set the tube symmetrically between the pole pieces.
3. Take microscope readings without parallax.
4. Do not change the liquid column after filling the tube.

Viva Questions

1. Why does a paramagnetic liquid rise? It is attracted towards the region of stronger magnetic field.
2. What is susceptibility? It is the ratio of intensity of magnetisation to applied magnetic field.
3. Why is a non-uniform field required? A force acts on the liquid only when the field has a gradient.