Question

Sound is produced in a bamboo flute because:
(A) Air starts vibrating
(B) Bamboo starts vibrating
(C) Air hits the bamboo
(D) Direction of air is changed

Answer 1

Hint: To answer this question, we need to analyse the basic phenomenon of the production of sound. Then, we need to relate this phenomenon to the sound production in a flute.

Complete step by step solution:
We know that sound is a longitudinal wave which requires a medium to travel. It can travel in any medium, be it a solid, liquid or gas. In all these three kinds of medium, the basic phenomenon is the same. That is the molecules of the medium vibrate. There is a series of compressions and rarefactions of the molecules, that is, a variation in the density of the molecules of the medium.
So for the production of the sound in a medium, we need to impart energy to its molecules.
In the case of a bamboo flute, we do not play it by beating its material. So, we are not supplying energy to its molecules. Thus the molecules of bamboo cannot vibrate.
Therefore, option B is incorrect.
Also, the air is blown inside the bamboo flute to make it produce sound. The air will of course hit the bamboo, but the molecules of this material will not gain enough energy from the air so that they can start vibrating.
Therefore, option C is also incorrect.
The sound is produced due to the propagation of the series of compressions and rarefactions. So it will not depend on the direction in which the air is flowing.
Therefore, option D is also incorrect.
To produce the sound in a flute, we blow the air into it through our mouth. This basically imparts energy to the molecules of air present inside the fluid, which makes them vibrate.
Hence, the correct answer is option (A).

Note:
Do not get confused by the fact that the sound can also propagate in the solids. It is true, but the appreciable propagation of sound happens in the case of metals. In our case we have bamboo as the solid material, which is not a metal. So, almost no sound will be propagated inside bamboo.