Some examples of Pascal's principle, also known as the principle of transmission of fluid-pressure or Pascal's law, can be found in the operation of hydraulic jacks, hydraulic lifts and motor vehicle braking systems. According to Pascal's law, when pressure is exerted on an enclosed and incompressible fluid, that pressure is transmitted undiminished throughout the fluid. By exerting a force to a fluid at one end of a closed system over a small surface area, that same force can be transmitted to the opposite end of the system across a larger surface area with an increased magnitude.
Pascal's law is the foundation of the applied science of hydraulics. A small force applied to a small piston can produce a much greater fluid-transmitted force on a larger piston. If the larger piston is 50 times the size of the smaller piston, the force transmitted to the larger piston will be 50 times the force applied to the smaller piston. However, the law of conservation of energy is not violated because no additional energy is created in the process. If the small piston is pushed down 50 inches, the larger piston, which is 50 times the size of the smaller piston, will travel only 1 inch. The decrease in the distance moved at the end of the system compensates for the increase to the force applied at the beginning of the system.