Question

Why does the doorbell ring repeatedly when the switch is pressed?
A. Because of nature of current
B. Because electric switch is built in such a manner
C. Because of make and break arrangement
D. Because of slight humidity in the circuit

Answer 1

Hint: In order to answer this question we must be knowing that doorbell works on the principle of electromagnetism, in which electromagnets are used , where electromagnets in simple words are magnets which generates magnetic field with the help of electric current. Striker or hammer is one part of an electric bell which gets attracted by electromagnets when it gets magnetized and when its demagnetized hammer or striker moves away from it, this process causes continuous ringing of the bell.

Complete answer:
Before diving into answer directly lets know that a doorbell or we can also say it as a electric bell consists of following parts which are a U-shaped electromagnet, a hammer or striker, a gong (it’s just a hollow curved plate over which striker strikes and from it sound emerges), armature, adjustment screw and battery-switch combination.

As we know the doorbell works on the principle of electromagnetism. Now when someone presses the switch of the doorbell, the circuit gets completed or we can say current in the doorbell circuit starts flowing which also flows through U-shaped electromagnet and as explained above electromagnet is one type of magnet which generates magnetic field when electric current passes through it.

Now when an electromagnet generates a magnetic field it attracts the iron armature where at the top of the armature the striker is attached , so as the armature moves towards the electromagnet, the striker(hammer) strikes the gong and the bell starts ringing.

As the armature is attracted towards the electromagnet, the contact with the adjustment screw breaks which results in breaking of the closed circuit and stops the current. Now when there is no current no electromagnetism phenomenon occurs and armature returns to its initial position.This making and breaking of the circuit causes ringing of the doorbells repeatedly till the switch is pressed.

Hence, the correct answer is option C

Note: The doorbell is a simple electric circuit which rang as a current supply but the point to note is as soon as the hammer hits, circuit breaks and electromagnet is inactive. Because the hammer is flexible, it moves back to its original position. As soon as it reaches its original position , the circuit gets complete. This process repeats continuously.