Physics · Wave Motion and Sound
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For a certain organ pipe, three successive resonance frequencies are observed at 425, 595, and 765 Hz. The speed of the sound in air is 340 m/s. The pipe is:
- A
Closed pipe of length 1 m
- B
Closed pipe of length 2 m
- C
Open pipe of length 1 m
- D
Open pipe of length 2 m
To find out which organ pipe is used, first, we will take the ratio of 3 observed harmonics:
425:595:765
5x 85 : 7x 85 : 9x 85
Since each successive harmonic is an odd number; the organ pipe is most likely a closed one and 85Hz is common for all so it is the fundamental frequency or
f=425/5 = 85Hz
f=595/7 =85Hz
f=765/9= 85Hz
Now:
For fundamental frequency:
L =v/4f = 340/85x4 = 1m answer!
To find out which organ pipe is used, first we will take the ratio of 3 observed harmonics:
425:595:765
5x 85 : 7x 85 : 9x 85
Since each successive harmonic is an odd number;the organ pipe is most likely an closed one and 85Hz is common for all so it is fundamental frequency or
f=425/5 = 85Hz
f=595/7 =85Hz
f=765/9= 85Hz
Now:
For fundamental frequency:
L =v/4f = 340/85x4 = 1m answer!
Incorrect as per formula
Incorrect as per formula
Incorrect as per formula
Tagged under Physics · Wave Motion and Sound · 2017