The apparatus is used for the study of longitudinal sound waves of the phenomenon of acoustic resonance. It can also calculate very accurately the wavelength and the speed of sound.

It consists of a sturdy transparent plastic tube, almost 1 m and a diameter of about 40 mm, placed horizontally in a suitable base. From the one end of the tube enters a piston, which can easily slide over the whole length of the tube. At the other end of tube is adapted an appropriate loudspeaker 0.2W / 8Ω, which is connected with a low frequency generator.

From a suitable hole on either both sides enters a small crystal microphone, which can also be placed at any point inside of the tube. The microphone is connected at the vertical deflection input of an oscilloscope. There is also integrated measuring tape on the tube.

Inventor number: ΤΑ. 130.0