6 A tube filled with water has a valve at the bottom to allo

6. A tube filled with water has a valve at the bottom to allow the water to flow out of the tube. As the water is emptied from the tube, the length L of the air column changes. A 1024-Hz tuning för placed at the opening of the tube. Water is removed from the tube until the n 5 mode of a sound wave resonates. What is the length of the air column if the temperature of the air in the room is 18 °C? [0.42 m?])

Solution

Speed of sound at 18 deg C,

v = 342 m/s

wavelength = v / f = 342 / 1024 = 0.334 m

wavelength = 4 L / n

for n = 5

L = 5 x 0.334 / 4

L = 0.4175 m