Question

A metal hammer hits a spherical bell, when the circuit in a calling bell is switched ON, the propagation of sound takes place due to
A. air
B. electric current
C. metal bell
D. none of the above

Answer 1

Hint: Recall the condition necessary for the propagation of a sound wave from one place to the other place. Check which of the options given satisfy the necessary condition for the propagation of the sound or sound wave.

Complete step by step answer:
The sound is produced in a calling bell circuit. The electric current is required for the working of a calling bell circuit. But it is not necessary for the propagation of the sound wave.
Hence, option B is incorrect.

The metal bell is one of the components in a calling bell circuit. But it is the component in the circuit which produces sound and does not help in the propagation of the sound.
Hence, the option C is incorrect.

When the circuit in a calling bell is switched ON, It starts ringing when switched by anyone using the button.
When someone switches the button of the calling bell, the metal hammer in the system hits the spherical metal bell and the sound is produced.
The propagation of this produced sound needs a medium which can be air.
Therefore, the propagation of sound takes place due to the air.

Hence, the correct option is A.


So, the correct answer is “Option A”.

Note:
 The students may assume that the metal bell in the calling bell circuit is necessary for the propagation of the sound wave. But it is the reason to produce the sound and not the requirement for the propagation of the sound from one place to the other place.
The medium required for the propagation of the sound wave may be anyone and not only air.