Sound signal is sent through a composite tube as shown in the figure. The radius if the semicircular portion of the tube `r`. Speed of sound in air is `v`. The source of sound is capable of giving vaied frequencies in the range of `v_(1)` and `v_(2)` (where `v_(2) gt v_(1)`). If `n` is an integer then frequency for maximum intensity is given by

Options

A. `(nv)/(r)`
B. `(nv)/(r(pi - 2))`
C. `(nv)/(pir)`
D. `(nv)/((r - 2)pi)`

Answer

B

Explanation

path difference `= pir - 2r`
`DeltaS = r(pi - 2) , nlambda = DeltaS`
for constructive interference
`nlambda = r(pi - 2) , lambda = (r(pi - 2))/(n) , n = (V)/(lambda) = (Vn)/(r(pi - 2))`