`S_(1)`: Source and observer both are stationary and wind is blowing in a direction from source to observer then observer detects an apparent increases in frequency.
`S_(2)`: Beat frequency is defined as the difference of frequency of two sources.
`S_(3)`: Pressure node is always a displacement node and pressure antinode is always a displacement antinode.

Options

A. TFT
B. FTT
C. FFF
D. TTT

Answer

C

Explanation

`f=((vpmv_(0))/(vpmv_(s)))f_(0)`
Here, `v_(0)=v_(s)=0`
So, `f=f_(0)`
In standing wave formation in a close organ pipe pressure node is a displacement antinode beat frequency `|f_(1)-f_(2)|` it cannot be negative.