The term tensiometer applies to a devices to measure the surface tension of liquids. Surface tension is a property of the surface of a liquid that allows it to resist an external force.
The Wilhelmy Plate tensiometer requires a plate to make contact with the liquid surface. It is widely considered the simplest and most accurate method for surface tension measurement.
A Wilhelmy plate is a thin plate that is used to measure equilibrium surface or interfacial tension at an air–liquid or liquid–liquid interface. In this method, the plate is oriented perpendicular to the interface, and the force exerted on it is measured.