Figure shows a tube structure in which a sund signal is sent from one end and is received at the other end.The semicircular part has a radius of 20.0 cm. The frequency ohet sound source can be varied elertronically between 1000 and 4000 Hz. Find the frequencies at which maxima of intensity are detected. The speed of sound in air =`3400ms^-1`.

Explanation

Path difference `Delta x = pi r - 2r = (pi - 2) r`
For maximum intensity
`Delta x = n lambda`
`(pi - 2)r = n lambda = (nv)/(f)`
`f = (n v)/((pi - 2))r = (n xx 340)/((3.14 - 2) xx0.2)`
` = 1491 n Hz`
` n = 1, f = 1491 Hz`
`n = 2, f = 2982 Hz`
`n = 3, f = 4473 Hz`
The frequencies in the given range are `1491 Hz` and `2982 Hz.`