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JAMB Physics 2014 Question 28

Question 28

Sound

The diagram above shows a stationary wave of wavelength 40 cm in a closed tube. The length L of the resonating air column is

Diagram for this question
  1. A.10 cm.
  2. B.20 cm.
  3. C.30 cm.
  4. D.40 cm.
Show the answer and explanation

Answer: C (30 cm.)

Explanation

The diagram shows one and a half loops, i.e. three quarter-wavelengths: L = 3λ/4 = 3 × 40 ÷ 4 = 30 cm.