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JAMB Physics 1990 Question 31

Question 31

Sound

In a resonance tube experiment, the effective length of the air column for the first resonance is 20 cm when set into vibration by a tuning fork of frequency 480 Hz. Neglecting end effect, the velocity of sound in air is

  1. A.96 m s−1
  2. B.255 m s−1
  3. C.340 m s−1
  4. D.384 m s−1
Show the answer and explanation

Answer: D (384 m s−1)

Explanation

First resonance: L = λ/4, so λ = 80 cm. v = fλ = 480 × 0.8 = 384 m s−1.