Kundt's Tube Research Articles

Kundt's Tube Projection Demonstration

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Preparing Rods for Stroking in the Kundt's Tube Experiment

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Ultrasonics in fluids.

DURING the recent meeting of the British Association at Newcastle upon Tyne, Section A (Mathematics and Physics) held a symposium on ultrasonics in fluids. Most of the papers read at this symposium, concerned applications of the ultrasonic interferometer, which may be regarded as a modern development of the familiar Kundt's tube into a precision instrument for studying those properties of gases and liquids which come into play when the molecules are set into vibration as a whole. In essence, the instrument consists of a quartz crystal in piezo-electric vibration, sending out plane waves into the fluid which are reflected back to the crystal, there to react upon the circuit which maintains the piezo-electric oscillations. The reflector usually consists of a plate mounted on a micrometer screw which is carried parallel to itself in a direction perpendicular to the ultrasonic wave-front, thereby recalling several types of optical interferometer. In the original method of Pierce, the magnitude of the resonance, as indicated by the maintaining circuit, at each half wave-length shift of the screw is observed through the change in the anode current of the circuit. With some precautions, the magnitudes of these current changes may be used to calculate the absorption coefficient of the radiation in the fluid, and, of course, the screw settings for these resonances enable the velocity in the fluid to be calculated if the frequency of the crystal oscillations can be accurately measured.

The Velocity of Sound in Vapors

The study of sound propagation in gases has revealed useful data concerning molecular behavior. Vapors, with little known about their absorption and dispersion to sound at audible frequencies, provide a natural field for extending such studies. In the present investigation, a form of Kundt's tube is employed in which a hot wire records the amplitude in the stationary wave system. It is calibrated by the use of dry air and of oxygen. The results obtained for the velocity of sound are in good agreement with those determined by other methods.

An improved Kundt's tube

An improved Kundt's tube

A Study of the Effect of Frequency and Temperature on the Velocity of Ultrasonic Waves in Gases

Measurements of the velocities of ultrasonic waves were made in carbon dioxide, nitrous oxide, and sulphur dioxide at temperatures from 30°C to 150°C. The fundamentals of seven quartz oscillators were used to obtain frequencies from 40 kc/sec. to 105 kc/sec. The gases were heated by passing them through a coil of copper tubing surrounded by a heating unit, both being wound around the gas chamber in which wave-length measurements were made. This chamber was a modified Kundt's tube with movable reflector for producing standing waves. The reflector was carried by a screw with a pitch of one millimeter and a dial graduated in hundredths of a millimeter. As the reflector passed through the nodes and loops the varying amount of energy reabsorbed by the electric circuit made it possible to determine the wave-length by the reaction of a radiofrequency milliammeter in the energizing circuit. The frequencies of the oscillators were determined by a frequency meter constructed for this work and calibrated by beating with WLW. The velocities thus obtained were reduced to 0°C and plotted against temperature at which the measurements were taken. In all three gases the velocity increases with increasing frequency but the increase is greater in carbon dioxide than in the other two gases. The velocity (V0) at any frequency is practically constant at all temperatures in N2O and SO2, but in CO2 the curve is flat for the lower temperatures, decreases rapidly by from six to ten meters per second in the temperature range from 50° to 130°, and again becomes constant at the higher temperatures.

Dust Figures in a Kundt's Tube

An experimental investigation of Kundt's tube phenomena has been performed with the primary purpose of investigating the actual motions and appearances of the striations under different conditions. No attempt was made to formulate rigorous theories explaining the figures. Very clear photographs of the particles in a striation were made by causing the striation to move out to the end of the tube and remain stationary long enough to be photographed. Photographs were also taken through the eyepiece of a microscope. From these it was evident that the particles in a striation did not, in general, touch each other. Striations on either side of a long metal rod on the bottom of the tube usually showed different spacings and occurred in different numbers on either side. This could not be caused by overtones since it is unlikely that more overtones could exist on one side than on the other. An electrostatic charge in motion near the tube prevented the figures from forming. A stationary charge in no way prevented their formation. Figures destroyed by the motion of a charge would slowly build up again when the charge was brought to rest, even with the charge present.

A Magnetostriction Oscillator Producing Intense Audible Sound and Some Effects Obtained

Apparatus is developed capable of pushing the magnetostrictive oscillation of nickel to the limit set by its mechanical strength. The intense audible sound produced is introduced under water from beneath the surface, continuous operation of the vibrator being secured by spray cooling. The interiors of corks are charred to cinder by the sound. A fountain 6 cm high forms on the surface of water, and is proved to be due to pumping action of the reciprocating rod and not to radiation pressure. Erosion of metals and of glass by cavitation and resultant water hammer is obtained. Colloids of oil and of carbon in water are produced. Curious fatigue effects in glass are observed. Whitened appearance and erratic motions of air bubbles released in water in the presence of the sound are observed, and theory is developed to explain these and the ``atomization'' of liquids. Flattening of a drop of liquid against a vibrator is observed and attributed to sonic attraction and to the reaction of sonic radiation. Frogs, fish, larvae, and water fleas are killed by the sound. Bacteria are killed so quickly that partial sterilization of milk in continuous process is effected. Striations in a Kundt tube that are parallel to its axis are produced, and an explanatory theory developed.

Velocity of Sound in Tubes at Audible and Ultrasonic Frequencies

The velocity of sound in air contained in glass tubes ranging in diameter from 0.1 cm to 3.0 cm was measured at ultrasonic frequencies over a frequency range from 30 to 200 kilocycles per second by using quartz crystals as sound oscillators, and the Kundt's dust tube method. The results do not agree with those calculated by use of Helmholtz-Kirchhoff equation ${V}^{1}={V}_{0}(1\ensuremath{-}\frac{C}{2R{(2\ensuremath{\pi}N)}^{\frac{1}{2}}}).$ An equation of the form ${V}^{1}={V}_{0}(1\ensuremath{-}\frac{C}{{D}^{2}}\ensuremath{-}\frac{K}{D{(N)}^{\frac{1}{2}}})$ is fairly satisfactory for both audible and ultrasonic frequencies. In this equation ${V}_{0}=331.77$ m/sec., $C=0.001512$, $K=0.174$, $N=\mathrm{frequency}$ and $D=\mathrm{diameter}\mathrm{of}\mathrm{the}\mathrm{tube}$. The agreement between experimental and calculated values is better for the larger tubes than for the smaller.

Phenomena in a Sounding Tube

IN view of Prof. Andrade's recent communication on Kundt's tube effects,1 the following observations may be of interest. The experiments were carried out in 1927 but have not yet been published. In our case supersonic sound waves were used, and the effects did not differ greatly, contrary to Prof. Andrade's suggestion, from those he obtains with waves of audio-frequency.

A Modified Form of Kundt's Tube

A Modified Form of Kundt's Tube

An Experimental Study of Kundt's Tube Dust Figures

An experimental study of the dust striations in a Kundt's tube has been carried out using a loud speaker, operated from a vacuum tube oscillator, as a source of sound. It is found that the positions of the vibrator for maximum agitation of the dust is different for the case in which a loud speaker is used from that obtained when a stroked rod is used. The formation and behavior of the striations is described in detail. It is found that the spacing between the striations increases with the intensity of sound, decreases with an increase in pressure of the gas, and decreases with an increase in density of the dust material. A minimum spacing is found when the size of the dust particles is changed. The relation suggested by Cook that the ratio of the separation of the striations to the mean free path is a constant was tested but the results obtained indicated that such a simple relation does not exist.

A Modified Form of Kundt's Tube

A Modified Form of Kundt's Tube

The Formation of Striae in a Kundt's Tube

The Formation of Striae in a Kundt's Tube

The Formation of Striae in a Kundt's Tube

The Formation of Striae in a Kundt's Tube

The Formation of Striae in a Kundt's Tube

The Formation of Striae in a Kundt's Tube

XIII.Some observations on movements of particles in Kundt's tube

XIII.<i>Some observations on movements of particles in Kundt's tube</i>

New Phenomena in a Sounding Dust Tube

I HAVE found the clear photographs of the antinodal ring of dust in a Kundt's tube which were published in NATURE on Nov. 9, p. 724, by Prof. Andrade and Mr. Lewer of special interest inasmuch as, while using a rod excited tube and Kieselsaure powder, I observed (Phil. Mag., vol. 7, p. 523, March 1929) an antinodal cloud and stated that “the antinodes are marked almost as definitely as the nodes”. As the dust was photographed when the note had ceased, a photograph as detailed as that of Prof. Andrade and Mr. Lewer was not obtained, although a ring-like grouping at the antinode is clearly suggested in Fig. 7 (c′) (1.c.).

CI.On the effect of constrictions in Kundt's tube and allied problems.—II.Some theoretical considerations

CI.<i>On the effect of constrictions in Kundt's tube and allied problems</i>.—II.<i>Some theoretical considerations</i>

LXI.Studies in the formation of Kundt's tube dust figures—Parts I. and II

LXI.<i>Studies in the formation of Kundt's tube dust figures—Parts I. and II</i>