An electromechanical relay consists of a coil, a core, contacts, an armature, and a spring. The core is typically made from iron or other ferromagnetic materials, which enhance the magnetic field produced by the energized coil. The armature, which is attached to the contacts, is the part that moves in response to the magnetic field. When current flows through the coil, it generates a magnetic field that pulls the armature toward the core, changing the state of the contacts. Once the current is removed, the spring mechanism returns the armature to its original position, restoring the contacts to their initial state.