A tuning fork of frequency gives resonance in a pipe closed at one end when the air column is long and again when it is long. What is the speed of sound in the air?
Answer and explanation
Correct answer: B. 331.5 m/s
- Step 1: In a resonance tube apparatus (closed organ pipe), successive resonance lengths occur at consecutive odd quarter-wavelength harmonics ( and ), so the difference between two successive resonance positions eliminates the end correction: .
- Step 2: Substitute and to find wavelength: .
- Step 3: Use the wave speed equation with frequency : .
Answer
331.5 m/s.
Why not the others: ignores end correction by naively setting .
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