What is solenoid action?

• A. The movement of the core in response to the magnetic pull of the coil
• B. The rotation of a rotor due to electrical current
• C. The generation of a magnetic field by a coil
• D. The switching of a transistor by a coil

Answer: (A)

Solenoid action is the linear movement of the magnetic core (plunger) caused by the magnetic field created when current flows through the coil. The coil’s magnetic field pulls the soft iron core into or out of the coil, producing straight-line actuation. This distinguishes it from spinning actions (rotating a rotor) or from simply generating a magnetic field or triggering a switch—the defining feature is the core’s linear motion driven by the coil’s magnetism. Solenoids are used in valves, locks, and other devices where straight-line actuation is needed.