The fundamental frequency of a closed organ pipe of length `20cm` is equal to the equal to the second overtone of an organ pipe open at both the ends. The length of organ pipe open at both the ends is

Options

A. `100cm`
B. `120cm`
C. `140cm`
D. `80cm`

Answer

B

Explanation

Here, `L_(C)=20cm`
Frundamental frequency of closed organ pipe
`=(upsilon)/(4L_(C))`
2nd overtone frequency of open organ pipe `=(3upsilon)/(2L_(0))`
As per question,
`(upsilon)/(4L_(C))=(3upsilon)/(2L_(0))`