CENCO Kundt's Apparatus
Measure the Velocity Sound
Here's a classic and elegant niniteenth century experiment that's still popular in an age of electronic and computer measurements. The apparatus consists of a glass tube one meter long. One end of the tube is closed with a stopper and the other end is open. An aluminum rod, with a disk on one end slightly smaller than the diameter, is inserted into the open end. By moving the rod and disk, students can vary the effective length of the vibrating column of gas in the tube. You set the rod into vibration at its natural frequency by stroking it with a piece of rosined leather to creat a high pitched note. The dust or powder inside the tube will collect into heaps at the nodes. The wavelength of the standing waves is then determined from the separation of the dust heaps. From this you can calculate the speed of sound. Includes instructions. Requires Lycopodium Powder or Cork Dust and a piece of leather and rosin. Overall length is 112cm.