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JAMB Physics 1983 Question 1

Question 1

Sound

In a resonance tube experiment, a tube of fixed length is closed at one end and several tuning forks of increasing frequency used to obtain resonance at the open end. If the tuning fork with the lowest frequency which gave resonance had a frequency f1 and the next tuning fork to give resonance had a frequency f2, find the ratio f2/f1.

  1. A.8
  2. B.3
  3. C.2
  4. D.½
  5. E.⅓
Show the answer and explanation

Answer: B (3)

Explanation

A tube closed at one end resonates at L = λ/4, 3λ/4, 5λ/4…, so its resonant frequencies are f, 3f, 5f… The next one after the lowest is 3 times it.