A sound wave of frequency 100 Hz is travelling in air. The speed of sound in air is `350 ms^-1` (a) By how much is the phase changed at a given point in 2.5 ms ? (b) What is the phase difference at a given instant between two points separated by a distance of 10.0 cm along the direction of propagation ?

Answer

`pi//2`

Explanation

Angular frequency is `omega = 2pin = 200 pi rad//s`
(a) phase change `phi = omegadeltat = 200 pi xx 2.5 xx10^(-3)`
= `(pi)/(2)`
(b) phase difference
`phi = (2pi)/(lambda). Delta`
`(200pi)/(350) xx 0.1 = (2pi)/(35)`Rad`