What statement is correct about relays?

What statement is correct about relays?

• A. There is normally an air gap between the armature and iron core to ensure the relay will drop out when de-energized.
• B. The armature is always in contact with the iron core.
• C. Relays operate without any magnetic interaction.
• D. The coil itself is the only moving part.

Answer: (B)

Relays switch circuits by using the electromagnet’s pull to move a metal armature that carries the switch contacts. When the coil is energized, the magnetic field pulls the armature toward the iron core, and that motion closes or opens the contacts to change the circuit connection. The armature is the moving piece that directly interacts with the magnetic circuit formed by the core, so it is effectively part of that magnetic path. That interaction between the armature and the iron core is the essential idea: the armature is drawn toward the core by the energized coil, producing the switching action. The other statements don’t fit the typical relay behavior: some designs include a small gap for release, but this is not what all relays rely on, so saying there is normally an air gap isn’t universal; relays rely on magnetic interaction, not a lack of it; and the coil is not the only moving part—the armature (and sometimes the contact assembly) moves to make or break the circuit.

Relays switch circuits by using the electromagnet’s pull to move a metal armature that carries the switch contacts. When the coil is energized, the magnetic field pulls the armature toward the iron core, and that motion closes or opens the contacts to change the circuit connection. The armature is the moving piece that directly interacts with the magnetic circuit formed by the core, so it is effectively part of that magnetic path.

That interaction between the armature and the iron core is the essential idea: the armature is drawn toward the core by the energized coil, producing the switching action. The other statements don’t fit the typical relay behavior: some designs include a small gap for release, but this is not what all relays rely on, so saying there is normally an air gap isn’t universal; relays rely on magnetic interaction, not a lack of it; and the coil is not the only moving part—the armature (and sometimes the contact assembly) moves to make or break the circuit.