What is Quincke’s Tube?

Hint: Quincke's method is used to determine the magnetic susceptibility of diamagnetic or paramagnetic substances in the liquid form or the form of an aqueous solution.
A magnetic moment is induced in a magnetic field when an object is kept in it.
Quincke’s method, like Gouy’s method, belongs to the former class.

Complete step by step answer:
This Method is designed for the determination of the magnetic susceptibility of a given solution. The setup has a pair of electromagnets and a Quincke's Tube here, the sample is taken.
This tube has the shape U and has two limbs, one with a very narrow width compared to the other. The change in the liquid level of the narrow limb does not affect the liquid level in the wider limb. The digital Gauss meter is used to measure the magnetic field.
In this apparatus, the rise in liquid by the application of a magnetic field is measured by a traveling microscope. This method is used to determine the magnetic susceptibility of paramagnetic substances in the form of liquid or aqueous solutions.
This method is described by the force experienced by a magnetized material in a non-uniform magnetic field. If the object is placed in a magnetic field, a magnetic moment is induced in it.
Magnetic susceptibility is dimensionless which refers to the degree of magnetization of a material in response to an applied magnetic field.
A sample in a narrow tube placed between the poles of a magnet experiences a force, and hence when the field is turned on, the meniscus in the narrow tube increases by an amount h, relative to its zero-field position.

Note:
Quincke’s tube is a method apparatus that is used for determining the magnetic susceptibility of the given solution.
The U-shaped tube has two limbs. One limb tube has a narrower width than the other limb.
The narrow limb liquid does not change when the level in the wider limb.