Question

The diagram shows the circuit of a doorbell. What happens when the bell button is switched on and switched off?

	Switch on	Switch off
A	1 ting is heard	Silence
B	1 ting is heard	1 ting is heard
C	Continuous ringing	Silence
D	Silence	Continuous ringing

Answer 1

Hint: When current flows through the coil of the electromagnet, it becomes attracted to the soft iron. When the current stops flowing, its attractiveness stops.

Complete step by step answer:
In the above diagram, we see the circuit diagram of a bell, which is in an off position. The bell and its circuit composed of a cell, a switch, an electromagnet, a metal strip (usually attached to a spring), a soft iron, a hammer, and a gong 1 and 2.
The working operation of the electric bell above is simple, and it goes as follows.
When the switch of the bell is closed, which is the button a person presses to ring the bell, current starts to flow through to the electromagnet. Then the electromagnet becomes attractive to the soft iron right in front of it, which moves towards the electromagnet. While doing this the hammer attached to the lower end of the soft iron collides with the gong, and a sound is heard. The soft iron remains there until the switch is released. Then electromagnet stop attracting the iron, and the soft iron returns to its initial position due to its springy metal strip. The hammer striking the second gong in the process. Hence, for one simple press and release, two sounds are heard, “ding dong”.
Hence, at switch-on, one sound is heard, and at switch off, another is heard.
Hence, the correct option is B.

Note: For clarity, the electromagnet is just a coil of wire which runs around some metal within it. This coil must be insulated so the current does not get to the metal itself. If that happens, the metal stops acting as a magnet but as a conductor.