How Calling Bell Works?

How Calling Bell (Door Bell) Works?

In this post, we will see the working principle of calling bell in simple language. Before that just understand the construction of calling bell also known as door bell.


As shown in the above figure, it has a solenoid or a coil winding.

  • A circular rod (conductor) embedded with a spring is placed in the centre of the coil winding.
  • The rod can be freely move front and back.
  • The solenoid is an electromagnet.
    ie when it gets the electrical energy, it induces a magnetic flux and acts as a magnet.
  • Both the sides of this arrangement, bars are placed with proper support.

Working Principle of Calling Bell:

The calling bell(Door bell) works as per Faraday's law of electromagnetic induction.
The working is given by step by step.

  1. The two wires came out of calling bell is connected across the switch kept outside the house.
  2. When the switch is pressed, it closes the circuit. So the coil gets energized and it becomes electromagnet.
    calling_bell_Ding_SoundAs per Faraday's law, it pulls the freely suspending conductor towards it. Consequently it will hit the A-bar. This will produce the Ding sound.
  3. When we release the switch, the electromagnet collapses. So it will release the conductor rod.
    calling_bell_Dong_SoundConsequently it will hit the B-bar. This action will produce the Dong sound.
  4. You can observe that among the two sounds, the Ding sound will be more powerful(it has more volume) and the Dong sound will be less powerful ( comparatively less volume).
  5. This is due the reason that the ding sound is produced by power stroke and the dong sound is produced by release stroke.

Still not clear and having any questions???... Please share in the comments section.....

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  1. Subham says:

    It's very very helpful for all thanks

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