Question

Explain why (or how):

(a) In a sound wave, a displacement node is a pressure antinode and vice versa,

(b) Bats can ascertain distances, directions, nature, and sizes of the obstacles without any “eyes”,

(c) A violin note and sitar note may have the same frequency, yet we can distinguish between the two notes,

(d) Solids can support both longitudinal and transverse waves, but only longitudinal waves can propagate in gases, and

(e) The shape of a pulse gets distorted during propagation in a dispersive medium.

Answer 1

(a) yes
we know, at node displacement of wave is zero. But pressure is maximum whereas on antinode displacement is maximum and pressure will be zero.


(b) yeah , this is because Bat produced and received ultrasonics waves. They have developed ' Echo location system' , by which they can ascertain distances , direction , nature and sizes of the obstacle without any ' eyes' .


(c) This is because the nature of waveforms and presence of overtone are different in the two cases .

(d) For transverse wave propagation the medium must have the property of sustaining shear or shearing .
We know, Gases can't sustain shearing stress so, they can't support transverse wave .


(e) A pulse is the combination of waves having different wavelengths. These wave travel in a dispersive medium with different Velocities , depending on the nature of the medium . This results the shape of pulse gets distorted during propagation in a dispersive medium.