Kundt’s tube

How it works:

The exhibit shows the phenomenon of a standing wave. A loudspeaker is mounted tightly to a see-through pipe. From the loudspeaker, a sine wave is emitted. The goal is to find the correct frequency for the standing wave to occur. It is achieved by turning the knob, which changes the sound frequency. The wave is visualised thanks to coloured styrofoam particles inside the tube. When the standing wave appears, the air inside starts to vibrate strongly and the particles move along, projecting the shape of the wave.

How it’s made:

The exhibit consists of a flat base, about 2 m wide, with two 1,4 m tall columns on each side. Between the columns a Φ80 mm see-through plastic pipe is mounted. At one end of the pipe, there is a loudspeaker. The sound generator and amplifier are hidden inside the column. On the left column, there is a multiturn knob, used for sound frequency adjustment. The design is made from lacquered MDF boards.