In a solenoid, which component is attracted by the magnetic field to produce mechanical motion?

• A. Plunger
• B. Rotor
• C. Core
• D. Armature

Answer: (D)

In a solenoid, the moving part is the piece that the magnetic field pulls to create motion. When current runs through the coil, it generates a magnetic field that attracts a ferromagnetic piece; this movable element is called the armature. It’s the armature that translates the magnetic attraction into linear motion, often pulling in or pushing out to actuate a valve or switch. The core serves mainly as a magnetic path and stays in place, so it doesn’t produce the mechanical motion. A rotor is associated with machines that rotate, not with typical solenoids. In many designs the plunger is simply the type of armature, but the general term for the moving part driven by the magnetic field is armature.