NEET Solved Paper 2018 Question 2
Question: The fundamental frequency in an open organ pipe is equal to the third harmonic of a closed organ pipe. If the length of the closed organ pipe is 20 cm, the length of the open organ pipe is [NEET - 2018]
Options:
A) 12.5 cm
B) 8 cm
C) 13.2 cm
D) 16 cm
Show Answer
Answer:
Correct Answer: C
Solution:
For closed organ pipe, third harmonic $ \text{=}\frac{3v}{4l} $
For open organ pipe, fundamental frequency $ =\frac{v}{2l’} $ Given, $ \frac{3v}{4l}=\frac{v}{2l’} $
$ \Rightarrow l’=\frac{4l}{3\times 2}=\frac{2l}{3} $ $ =\frac{2\times 20}{3}=13.33cm $
