Physics Project 2008

Kundt's Tube

Faculty Mentor - Thomas Meyer, Vladimir Gasparayan

The purpose of the Kundt's Tube was to find the speed of sound in a metal rod. During this experiment, we had to find the speed of sound in standing longitudinal waves in a column of air inside of a glass tube and determine the velocity of sound in a metal rod. Sound waves are produced by a rod which is made to vibrate at its natural frequency (See Figure above), producing disturbances in the various materials used, which indicated the presence of the standing waves and permit measurement of their wavelength (see Eq. 2). We were originally supplied with an aluminum rod and cork dust, which is to be distributed liberally along the entire length of the tube, about 2 mm thin. We expanded our experiment and used a brass and copper rod as well. All rods were 81.4 cm long. As for materials in the tube, we used a range of organic and inorganic materials, such as cork dust, instant coffee, Splenda artificial sweetener, car paint dust (primer, Bondo, and paint), cocoa powder, lycopodium, parsley dust, diatomaceous earth, and espresso coffee. We also used smoke balls and cigarette smoke in the tube.

Speed of Sound

Faculty Mentor - Thomas Meyer, Vladimir Gasparayan

The purpose of the project was to examine changes in the speed of sound under varying conditions of temperature, pressure, and gas. A sound wave is a pressure disturbance that travels through a medium as a series of compressions (areas of high density) and rarefactions (areas low density). This "squeezing" wave travels through air or other media at a rate that depends on several factors including temperature, pressure, and nature of the medium. The effect of these variables on the speed of sound was examined in this experiment by accurately taking measurements at room temperature and atmospheric pressure and making comparisons to values measured under varying conditions. Measurements were made using a sound tube, microphone, thermometer, oscilloscope, and sound emitter. Sound waves traveling through the tube were shown to speed up and slow as conditions changed. The results were consistent with expected values obtained from theoretical descriptions of these phenomena.