What is Pascal’s Law?: Definition with Example

Pascal’s Law: The French scientist Blaise Pascal observed that the pressure in a fluid at rest is the same at all points if they are at the same height. In other words if gravitational attraction is negligible in equilibrium condition pressure is same at all the points. If external pressure is applied to an enclosed fluid it is transmitted undiminished to every direction.  The SI unit of pressure  is pascal.


o   Consider a vessel of circular shape filled with water which has 4 openings and in the entire openings 4 pistons are attached.

o   Apply force on the first piston; this piston will move inward and all other pistons will move outwards.

o   This happens because when this piston moves inwards the pressure is exerted on the water.Water transmits this pressure in all the directions.

o   The other pistons,except A, moves at the same speed which shows water has exerted pressure in all the directions.