Kundt, August Adolph Eduard Eberhard (1839-1894)

German physicist who in 1866 invented Kundt's tube, a simple device for measuring the velocity of sound in gases and solids. His later work entailed the demonstration of the dispersion of light in liquids, vapours, and metals.

Kundt was born in Schwerin, Mecklenburg, and educated at Leipzig and Berlin. He was professor at the Polytechnic in Zürich, Switzerland, in 1868, at Würzburg from 1869, and was one of the founders of the Strasbourg Physical Institute in 1872. He ended his career as director of the Berlin Physical Institute from 1888.

Kundt's tube is a glass tube containing some dry powder and closed at one end. Into the open end, a disc attached to a rod is inserted. When the rod is sounded, the vibration of the disc sets up sound waves in the air in the tube and a position is found in which standing waves occur, causing the dust to collect at the nodes of the waves. By measuring the length of the rod and the positions of the nodes in the tube, the velocity of sound in either the rod or air can be found, provided one of these quantities is known. By using rods made of various materials and different gases in the tube, the velocity of sound in a range of solids and gases can be determined.