An open pipe is suddenly closed at one end with the result that the frequency of the third harmonic of the closed pipe is found to be higher by 100 Hz than the fundamental frequency of the open pipe. The fundamental frequency of the open pipe is:
Correct answer: A. 200 Hz
- A. 200 Hz
- B. 300 Hz
- C. 240 Hz
- D. 480 Hz
Explanation
Following is the solution to this question:Fundamental frequency in an open organ pipe: f = v/2LFrequency of 3rd harmonic in a closed organ pipe: f3 = 3v/4LWe know from the statement in the question that: f3 - f = 100therefore:3v/4L - v/2L = 100v/L = 400Thus fundamental frequency in an open organ pipe: f = v/2L = 400/2 = 200Hz
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Progressive waves transfer energy through oscillations, with wavelength, frequency, amplitude and wave speed related by v = fλ; sound speed depends on the medium. Superposition produces interference and stationary waves in strings and organ pipes, while simple harmonic motion describes the oscillation itself and must be distinguished from wave propagation.
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