Question

The time period of a sound wave travelling in a medium is T. At a given instance (t=0) a particular region in the medium has minimum density. The density of this region will be minimum again at a) t=T b) t=T/2 c) t=T/3 d) t=T/4

Answer 1

The correct option is a
Its a low or minimum density region  so it is rarefaction.
so from t=0, next rarefaction will be produced at
t=T/2+T/2=T

Answer 2

The density of this region will be minimum again at t = T. option a.

• The given region is of low or minimum density by which the time periods will be t = T/2+T/2 which is equal to T. (t=T)
• When the time period is zero at a minimum density, there would be refraction produced due to which time period would be T/2+T/2.
• Refraction refers to a change in the medium of a wavelength as it passes from one medium to another medium.
• When there is a change in medium, then the frequency, density, and other parameters also change.
• Therefore at a minimum density, time period t = T.