3.0. Tubo de Kundt EN

Kundt's tube


The Kundt’s tube is used to study the stationary waves.


In its original form, it consists of a tube made of glass blocked at both ends, one of them by a fixed cap and the other by a movable piston. This let us modify the length of the pipe, which contains, uniformly, some light materials such as lycopodium powder or crushed cork.


When the metal bar is hit, it produces a vibration which is spread through the air molecules that are contained in the tube. The result is a sound wave which is reflected in the contrary end of the tube. The interference between the direct wave and the reflected wave generates a set of standing waves that is made visible by the distribution of the light particles, since these begin to move and accumulate in the points where the waves interfere in a constructive way.


The experiences with this instrument, which were carried out for the first time in 1866, were the main contribution of the German physicist August Kundt to the acoustic field.