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EEJ MAIN Physics QUESTION #7078
Question 1
A pipe that is open at both ends has a fundamental frequency $f$ in the air. If the pipe is submerged vertically in water such that exactly half of its length is underwater, what is the new fundamental frequency of the air column?
  • $\frac{3f}{4}$
  • $2f$
  • $f$✔️
  • $\frac{f}{2}$
Correct Answer Explanation
An open pipe of length $L$ has $f = \frac{v}{2L}$. When half-submerged, it becomes a closed pipe of length $L/2$. The fundamental frequency of a closed pipe is $f' = \frac{v}{4(L_{new})} = \frac{v}{4(L/2)} = \frac{v}{2L}$. Therefore, $f' = f$.