What design feature in relays helps ensure they release when de-energized?

• A. An air gap between armature and core.
• B. A magnetic shunt.
• C. A fully closed magnetic path.
• D. A permanently magnetized yoke.

Answer: (A)

When a relay needs to release the armature after the coil is turned off, the magnetic circuit must be interrupted so the attractive force vanishes. An air gap between the armature and the core creates a high magnetic reluctance, so once the current stops, the magnetic field collapses quickly and the armature is freed to move back by its restoring spring. This ensures a clean release and opening of the contacts.

A magnetic shunt would give an alternate low-reluctance path, helping keep flux in the core and making release slower or incomplete. A fully closed magnetic path keeps a continuous circuit even after power is removed, so the armature tends to stay attracted. A permanently magnetized yoke leaves residual magnetism that can continue to pull on the armature, hindering release.