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JAMB Physics 1985 Question 29

Question 29

Sound

If the fundamental frequency of a closed pipe organ on a day when the speed of sound is 340 m s−1 is 170 Hz, then the length of the pipe is

  1. A.50 cm
  2. B.70 cm
  3. C.100 cm
  4. D.150 cm
  5. E.200 cm
Show the answer and explanation

Answer: A (50 cm)

Explanation

λ = v/f = 340/170 = 2 m. A closed pipe's fundamental has L = λ/4 = 0.5 m = 50 cm.