Electric Bell: Diagram and Working Principle

To draw or understand the diagram, you need to identify its 5 main components:

1. U-shaped Electromagnet: A piece of soft iron core with insulated copper wire coiled around its two arms.
2. Armature: A soft iron strip placed just in front of the electromagnet.
3. Hammer: A metal ball attached to one end of the armature.
4. Gong: A hollow metal bowl that the hammer strikes to make a sound.
5. Contact Screw: An adjustable brass screw that touches the back of the armature, completing the circuit.

The bell operates on a rapid 'make-and-break' circuit mechanism.

• Step 1 (Switch ON): When you press the switch, current flows through the coiled wire. The iron core instantly becomes a powerful Electromagnet.
• Step 2 (Attraction): The electromagnet strongly pulls the soft iron armature towards itself. As the armature moves forward, the hammer strikes the gong, producing a 'Tring!' sound.
• Step 3 (The Break): Here is the trick! When the armature moves forward to hit the gong, it pulls away from the Contact Screw. The circuit is broken. The current stops flowing.
• Step 4 (The Return): Without current, the electromagnet loses its magnetism. A spring pulls the armature back to its original position.
• Step 5 (Repeat): The moment the armature touches the contact screw again, the circuit is completed, the electromagnet turns back on, and the whole process repeats rapidly, creating a continuous ringing sound.