Kundt's tube apparatus is a device for measuring the velocity of sound in air. Any waves traveling along the medium will reflect back when they reach the end creating a standing wave allowing harmonics to be identified. Nodes occur at fixed ends and antinodes at open ends. Furthermore, it provides an insight into the interesting phenomenon of standing sound waves.

    Comprises  cylindrical  tube 100 cm long and 3 cm in diameter approx.  is mounted in a 'Y shape  clamps on a metal base. A rod about 75 cm long is held firmly at its mid-point in a sturdy clamp at one end of the base. One end of the rod has a metal disc attached to it and projects into the glass tube. The other end of the tube is closed by a tight fitting piston mounted on the base.The 'Y' supporting the tube may be adjusted vertically and laterally until  the metal disc will not touch the glass.