Explain pressure measuring device at any point in fluid in short.

Explanation

An idealized form of pressure -measuring device is shown in the figure .

It consists of an evacuated chamber with a spring that is calibrated to measure the force acting on the piston.
This device is placed at a point inside the fluid.
The inward force exerted by the fluid on the piston is balanced by the outward spring force and is thereby measured .
The force `DeltaF` acting on the surface of the piston then pressure of fluid `P=(DeltaF)/(DeltaA)`
The piston area can be made arbitraaily small . The pressure is then defined in a limiting sense as `P=underset(DeltaAto0)(lim)(DeltaF)/(DeltaA)`