What is the typical working medium in a pneumatic system?

• A. Liquid
• B. Gas
• C. Solid
• D. Plasma

Answer: (B)

In pneumatic systems, energy and motion are transmitted by a gas, usually compressed air. Gases flow easily, can be compressed to store energy in a compact reservoir, and can be directed through hoses and valves to actuators for quick, controllable movement. This combination—flow, compressibility, and simplicity—is why air (a gas) is the typical working medium. If you used a liquid, you’d be in hydraulic territory, which serves different performance needs; solids don’t flow to transfer energy in this way, and plasma isn’t practical for standard industrial actuation.