Question

Two pipes are each 50 cm in length. One of them is closed at one end while the other is open at both ends. The speed of sound in air is 340 m s–1. The frequency at which both the pipes can resonate is

• A. 680 Hz
• B. 510 Hz
• C. 85 Hz
• D. None of these

Answer 1

Answer: (D)

None of these

Answer 2

A pipe open only at one end and another one of equal length but open at both the ends have their fundamental frequencies $\upsilon$and $2\upsilon$respectively. Again only odd harmonics are possible for a pipe open at one end whereas all second harmonics are possible for a pipe open at both ends. Thus, it is impossible to have a common frequency at which they can resonate.