A solenoid is comprised of copper wiring coiled around a Faraday tube and a metal plunger, and a spring. When the copper wire is charged, a magnetic field is activated, and the magnetic attraction pulls the metal plunger into the Faraday tube. When the electric circuit is switched off, a spring returns the piece to its original state. This system is typically utilized to create a pushing motion, used in a push/pull solenoid, or in controlling the movement of a valve, used in a pneumatic or hydraulic solenoid.
