Question

The diagram shows the circuit of an door bell. What happens when the bell button is switched on then switched off?

	Switch on	Swithc off
(A)	$1$ ting is heard	Silence
(B)	$1$ ting is heard	$1$ ting is heard
(C)	Continuous	Silence
(D)	Silence	Continuous ringing

• A. A
• B. B
• C. C
• D. D

Answer 1

Answer: (B)

B

In the given bell circuit, when we press the bell button (switched on), current will flow through the circuit and the solenoid will become magnetised. It will produce magnetic field that will attract the soft iron which will hit the gong 1. So a ting will be heard.

After switching off, the solenoid will become demagnetised and will not produce magnetic field. The soft iron won't be attracted. The hammer will come back to its mean position due to the pull of the spring metal strip. The other (right) face of the hammer will hit the gong 2. So another ting is heard.