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A pipe open at both ends has a fundamental frequency f in air. The pipe is dipped vertically in water so that half of it is in water. The fundamental frequency of the air column is now:

1. 2f
2. f
3. f/2
4. 3f/4

Correct answer: f

Solution

When the pipe is half submerged in water, the effective length of the air column that vibrates is halved, but since the pipe is open at both ends, the fundamental frequency remains the same. The frequency is determined by the speed of sound in air and the length of the air column, and since the length does not change in terms of the fundamental frequency calculation, it remains f.

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