A pipe of length 10 cm, closed at one end, has a frequency equal to half the 2nd overtone of another pipe open at both the ends. What is the length of the open pipe ?

Options

A. 10 cm
B. 20 cm
C. 35 cm
D. 30 cm

Answer

D

Explanation

For the closed pipe , ` n = V/(4l) `
For the open pipe ` n' = (3V)/(2l') `
But `n = (n')/2 :. V/(4l) = 1/2 (3V)/(2l') `
` :. L' = 3l = 30 ` cm