Question
Physics Question on Waves
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 20cm, the length of the open organ pipe is
A
16 cm
B
13.3 cm
C
12.5 cm
D
8 cm
Answer
13.3 cm
Explanation
Solution
For closed organ pipe, third harmonic =4l3v For open organ pipe, fundamental frequency =2l′v Given, 4l3v=2l′v ⇒l′=3×24l=32l =32×20 =13.33cm