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JAMB Physics 1998 Question 28

Question 28

Sound

In a resonance tube experiment, if the fundamental frequency of the vibrating air column is 280 Hz, the frequency of the third overtone is

  1. A.70 Hz
  2. B.840 Hz
  3. C.1120 Hz
  4. D.1960 Hz
Show the answer and explanation

Answer: D (1960 Hz)

Explanation

A resonance tube is closed at one end, so only odd harmonics occur: 280, 840, 1400, 1960 Hz. The third overtone is the 7th harmonic, 7 × 280 = 1960 Hz.