Doorbells are devices which work very easily, they are used every where houses, shops, banks etc .
The core of a conventional doorbell is an electromagnet. An electromagnet is " A core of magnetic materials surrounded by a coil of wire through which an electric current is passed to magnetize the core". The devices of doorbells work in a very simple way; first step off course is pressing the buzzer, pressing the buzzer allowed a current to move from the button to the transformer leading it to the contact arm. Where the current bounces forward and backwards through the arm, making it bounce up and down. The metal contact is connected directly to the electromagnet. Because the arm bounces it comes in contact with the metal; the electromagnet receives the bounce and produces the sound. It is known that the buzzing noise that the people hear is in fact the arm hitting the magnet and the stationary contact 12 times per second.
Electricity can flow through the electromagnet even when the circuit is closed, this is because of the way the contact arm has been designed, the contact arm is a thin piece of light conductive metal with a thin bar soldered onto it, the fixed end of the contact arm is wired to the electrical circuit, the end of the arm rests on the contact point when the electromagnet is turned off, therefore there is a connection between that end of the wire and the electrical circuit.
Doorbells have the same function as the buzzers, their function differs only because of the moving arm, and the moving arm is attached to a long clapper, which lies beside a circular bell. In this function the same steps happen, when they are functioned the arm moves back and forth, the clapper hits the bell constantly, to make it more clear; as we press the button we open the circuit, a current flows to the wire coils moving through the transformer. The solenoid piston is in contact with the left tone bar, when the circuit is closed it doesn't produce and sounds.
