Which principle states that pressure applied to a fluid is transmitted unchanged throughout the fluid?

• A. Archimedes Principle
• B. Pascal's Principle
• C. Bernoulli's Principle
• D. Boyle's Law

Answer: (B)

Pascal's Principle states that pressure applied to a confined fluid is transmitted undiminished throughout the fluid and to the walls of its container. In practice, this means a small push on a piston creates the same pressure everywhere inside the fluid, so the force can be distributed or amplified based on piston areas. For example, in a hydraulic lift, pushing a small piston with a certain force generates a pressure P = F/A that acts on a larger piston; because pressure is the same, the large piston experiences a larger force F = P × A, allowing mechanical advantage.

This idea relies on the fluid being confined and effectively incompressible, so the pressure change propagates uniformly rather than changing with location. It’s different from Archimedes’ principle, which explains buoyancy as the upward force equal to the weight of displaced fluid; Bernoulli’s principle connects pressure to fluid speed in moving streams; and Boyle’s law describes how gas pressure and volume relate at constant temperature.