Question

An open organ pipe of length L vibrates in its fundamental mode. The pressure variation is maximum
(a) at the two ends
(b) at the middle of the pipe
(c) at distance L/4 inside the ends
(d) at distances L/8 inside the ends.

Answer 1

An open organ pipe of length L vibrates in its fundamental mode. The pressure variation is maximum at the middle of the pipe.

Explanation:

• The basic mode of vibration is the minimum frequency at which the pipe forms a standing wave.
• For an open pipe organ, Where the basic vibration mode is set, Pressure nodes are found at the open ends because the air molecules are free to vibrate at these ends.
• This results in the formation of pressure antinodes between these two nodes at midway point, i.e. at the center of the pipe, and here the maximum variation in pressure is achieved.