Ripple Tank Research Articles

New Experiments on Wave Physics with a Simply Modified Ripple Tank

The ripple tank is one of the physics education devices most appreciated by teachers and students. It allows one to visualize various phenomena related to wave physics in an effective and enthralling way.1,2 Usually this apparatus consists of a tank with a transparent bottom that is filled with a thin layer of water. A source of light illuminates the water surface from the top and the water is mechanically perturbed in order to produce regular waves. With the water crests and troughs acting as converging and diverging lenses, the surface configuration is reproduced on a screen using a play of light and shadows. We propose a simple and cheap change to this tool. Such a modification could be constructed by pupils themselves in their school laboratory. The lighting in our apparatus differs from the usual arrangement: the light is somewhat oblique with respect to the water surface, and a system of screens with holes and slits is placed at the bottom of the glass tank. This allows us to select and illuminate small portions of water. In this way our modified ripple tank gives us the possibility to perform new experiments and to explain by further examples the properties of waves.

Imaging surface water waves for the determination of surface tension and spatial attenuation

We propose the use of the image analysis technique to determine the surface tension of water and the attenuation coefficients of surface water waves in terms of frequency. Tap water from two different locations is used in our experiments. Water waves are continuously generated at various frequencies in a ripple tank by a plastic blade driven by a function generator. Images of the water waves are then captured by a digital camera and analyzed by using Tracker. As a result, we obtain the surface tension of water at 25 °C from both locations that are in good agreement with those resulting from the capillary rise technique. In addition, a linear relationship between the attenuation coefficient of the water waves and driven frequencies, ranging from 40 to 90 Hz, can be observed. Our results indicate that the greater the surface tension the longer distance the water wave takes before its amplitude decreases to 1/e of its original value. This work brings forward a relatively simple technique that can be applied to determine the surface tension and attenuation coefficients of surface water waves in a ripple tank with notable results.

Hands-on demonstrations for Project Listen Up: Education outreach Part IV

Acoustical demonstrations geared to promote a hands-on learning experience for middle- and high-school age Girl Scouts are setup. The participants will be free to explore, control the apparatus and make their own scientific discoveries. The hands-on demonstrations will include (1) a home-made electric slide guitar using easy to find parts, (2) a safe smoke ring generator and (3) a portable ripple tank with plastic eyedroppers for simple excitation of waves.

Surface Bubbles in the Bathtub and Reflections on Ripple Tanks

Bathtubs are splendid places for studying physics! Recently I was happily splashing about and noticed that the light from the lamp above me was being focused as bright spots on the bottom of the tub. Closer inspection showed that the spots were surrounded by dark rings. This pattern turned out to be due to the lensing effect of bubbles floating on the surface of the water.

Hands-on demonstrations for Project Listen Up: Education outreach part III

Midshipmen will be getting involved in an ASA education outreach effort by presenting or recording a number of acoustical demonstrations geared to promote a hands-on learning experience for middle- and high-school age girl scouts. This is an extension of the demonstration effort and outreach presented at the ASA Meeting held in Baltimore in 2009 and Seattle in 2011. The demos are designed to visualize certain wave effects that will be explained by the Midshipmen “live” or by computer video. The participants will be free to explore, control the apparatus, and make their own scientific discoveries. The hands-on demonstrations will include (1) a ripple tank with two separated periodic point sources or a plane wave source driver for wave studies, (2) an ultrasonic motion sensor for measuring and displaying displacement, particle velocity and acceleration of an oscillating object or a person's motion, (3) tuning forks matched to Helmholtz resonators, and (4) a driven clamped circular plate supporting a column of dry sifted masonry sand (or uncooked rice or grass seed) for studying the resonant frequency versus. granular mass loading.

Demonstration and study of the dispersion of water waves with a computer-controlled ripple tank

The design of a ripple tank built in an undergraduate student project is described. Water waves are excited acoustically using computer programmable wave shapes. The projected wave patterns are recorded with a video camera and analyzed quantitatively. From the propagation of wave packets in distilled water at three different depths, the phase and group velocities are measured in the frequency range from 2 to 50 Hz. Good agreement with theory is found. The propagation of wave trains of different shapes is recorded and explained on the basis of the stationary phase approximation. Various types of precursors are detected. For a depth slightly above the critical depth and thus nearly dispersion-free, the solitary-like propagation of a single pulse is observed. In shallow water, the compression of a chirped pulse is demonstrated. Circular waves produced by falling water drops are recorded and analyzed.

Hands‐on demonstrations for Project Listen Up: Education outreach part II.

Midshipmen will be getting involved in an ASA education outreach effort by presenting or video taping a number of acoustical demonstrations geared to promote a hands‐on learning experience for middle‐ and high‐school age girl Scouts. This is an extension of the demonstration effort and outreach presented at the ASA Meeting held in Baltimore in 2009. The demos are designed to visualize certain wave effects that will be explained by the Midshipmen “live” or by video. The participants will be free to explore and then control the apparatus and make their own scientific discoveries. The hands‐on demonstrations will include (1) a ripple tank with an electronic wave height transducer for wave visualizations or making simple oscilloscope measurements, (2) a torsion wave machine for demonstrating reflection and interference effects, and (3) a forced damped harmonic oscillator apparatus that consists of a subwoofer driver connected to the bottom of a vertical spring that is attached at the top to a hanging mass on a string that is suspended over a pulley. Resonance effects can be easily observed watching the pulley oscillate around 1 Hz. The driver frequency is controlled by adjusting a single knob and looking at the digital display.

Hands-on demonstrations for Project Listen Up: Education outreach.

Midshipmen from the General Science Major will be getting involved in an ASA education outreach effort by presenting a number of acoustical demonstrations geared to promote a hands-on learning experience for middle- and high-school age girl scouts. The demos are designed to visualize certain sound wave effects that will be explained by the Midshipmen (role models) who hands-off the controls of the apparatus to the students who will be free to participate and make their own scientific discoveries. The demonstrations will be (1) sympathetic vibrations of matched xylophone bars or matched tuning forks mounted in quarter-wave resonant open-ended boxes, (2) tuning fork excitation of standing waves in a sound resonance tube with a variable water column, (3) small inexpensive speaker placed in a hole in a baffle or inside a megaphone generating enhanced sound by eliminating destructive interference effects, (4) interference from two separated loud speaker sources measured vs microphone location, and transverse wave visualizations using a (5) torsion wave machine and (6) a small ripple tank. The traveling and standing wave patterns in (5) and the reflection, refraction, interference, and scattering effects in (6) are helpful wave visualizations and aid in the understanding of longitudinal sound wave effects.

Creating a Virtual Ripple Tank in Microsoft Word

A ripple tank is an excellent apparatus for displaying the interference pattern generated by circular waves originating from two points in a shallow basin of water. What sets it apart from the interference by sources of sound and light is that it allows the interfering waves to be seen and measured (see Fig. 1). This paper describes a fairly quick way to investigate two-dimensional wave interference on a computer without putting that computer near a wet, sloshing tank of water. Microsoft Word was used for this purpose, although a wide range of other simple drawing programs may be employed.

Interaction of ultrasonic waves with structural damage: A diffraction analogy

This study investigates the interaction of ultrasonic waves and structural damage, i.e., cracking and corrosion. It is shown that cracking and corrosion damage produces a diffraction pattern that resembles that associated with the traditional physics of wave motion. The extension of this hypothesis implies that it may be possible to use a simple ripple tank to investigate how to best detect/sense and size a given damage state, e.g., corrosion. We also find that cracking, and corrosion damage, has a significant effect on both the amplitude and period of the waveform and also on the local (apparent) refractive index of the material and that these effects have the potential to be used as damage indicators.

Moving Sources: Doppler Beats and Mach Cones

This paper describes two experiments involving moving sources. The first one is a class activity for observing beats in a Doppler setup; the second one describes how to observe the transition from “subsonic” to “supersonic” waves in a ripple tank.

水面波投影装置の電子教材としての利用について

Hydraulics is considered as a difficult subject for undergraduate students in civil engineering, although it is the basic subject for understanding the environmental issues. A compact ripple tank is made so that the undergraduate students may be easy to understand visually the basic properties of the water waves such as reflection and diffraction. The Digital contents for lecture are developed using the experimental images demonstrated with the ripple tank. The digital contents are composed of the animations of experimental images and are opened to public on the homepage. Both experiments using the ripple tank and studies using the digital contents improve understanding the basic properties of water waves.

How Good Is the Approximation “Path Difference ≈ d sin θ”?

In standard textbook treatment the formula “path difference < d u” for the double-source interference pattern is justified for large distances only. Yet ripple tank patterns show that nodal lines become fairly straight not far from the sources. An analysis of the approximation is provided for nonasymptotic distances.

Computer simulations enhance experimental demonstrations in the underwater acoustics and sonar course

Underwater acoustics and sonar (SP411) is a 3 hour course that is offered to midshipmen in their senior year. Typically, general science and oceanography majors, totaling 110 students/yr, enroll. Since this course is offered without a lab, the ‘‘in class’’ experience has been enhanced with the development (over many years) of our demo carts and computer workstations which surround the classroom. In a studio classroom atmosphere, students perform a variety of experiments in small groups. How can scientific visualizations best develop learning of complex interactions? Two examples are presented. PC–IMAT (personal curriculum interactive multisensor analysis training) simulations of multielement array steering support the theory and enhance the experiments that are performed in class such as the two-element array. Mathematica simulations involving the programming and animation of a point source in a rigid–rigid infinite parallel wave guide are used to stress the method of images, superposition, group and phase velocity and far-field modal pattern that is observed as a function of depth and source frequency. Later, students have fun using a ripple tank with an eye dropper to generate a point source between two adjustable parallel boundaries, and their understanding of ‘‘underwater sound’’ is greatly enhanced.

Improvisation as a strategy for providing science teaching resources: an experience from Kenya

In Kenya, performance in science subjects has often been dismal. This poor performance is partly blamed on the increasing school enrolment, without a corresponding increase in teaching resources. The introduction of cost sharing in secondary schools has limited the government’s role to paying teachers’ salaries only. Capital development and purchase of teaching materials has been left to parents. Parents have been unable to carry out this role effectively because of increasing poverty levels in the country. The focus of this study was on how improvised science teaching aids provided through the teaching practice have influenced science teaching in schools. Evidence in this study has shown that schools, which hitherto have been unable to afford expensive gadgetry like ripple tanks, have done so through the teaching practice (TP) projects.

PEOPLE

PEOPLE

Quasilinear ridge structures in water surface waves.

Nodal patterns of stationary capillary waves formed on the surface of water enclosed in an agitated ripple tank with circular and stadium-shaped cylindrical walls are examined in the low-frequency (\ensuremath{\nu}50 Hz) and high-frequency (\ensuremath{\nu}g700 Hz) regimes. In the low-frequency regime, in agreement with predictions of quantum-chaos theory, the shape of the tank's boundaries (integrable or nonintegrable) dictates the type of nodal patterns obtained. In the high-frequency regime we obtain nodal patterns characterized by short-range order (called ``scarlets'' because they are believed to be the precursors of quantum scars), as recently predicted in the quantum-chaos context by P. O'Connor, J. Gehlen, and E. J. Heller [Phys. Rev. Lett. 58, 1296 (1987)].

The discovery of the Mach reflection effect and its demonstration in an auditorium

This paper examines the historical background leading to the discovery of the Mach reflection effect and applies original documents from Mach's residue which are kept in the archives of the Ernst-Mach-Institut in Freiburg. Two experimental setups for the generation and demonstration of the Mach reflection effect, incorporating an overhead projector, are described: (a) Mach's historic mechanical shock wave reflection and interaction experiments with soot covered glass plates, performed in 1875. The Mach triple points sharply erase the soot which results in a residual picture of funnel-shaped V-formations. The head-on collision of two shock waves is marked as a narrow line of piled-up soot. (b) CalTech's hydraulic jump reflection experiments in a shallow ripple tank, performed during World War II. Regular reflection and its transition into a Mach reflection wave. Using a slightly inclined tank and providing a “shoreline” in the middle of the tank, Mach stem propagation slows down to zero when hitting the shore line and, therefore, can be observed “live” without the use of a slow motion technique.

A ripple tank demonstration of the conditions for interference of waves

First Page

Water waves in a ripple tank

The profiles of water waves in a ripple tank were studied for various water depths. Wave forms with moderately large amplitudes varied with propagation at the depths of 0.5 and 1.0 cm due mainly to the nonlinear effects. The front faces of crests became steep, deviating appreciably from a sinusoidal form, and at 0.5-cm depth new ripples were excited in front of the steep forward face. At depths above 2 cm the waves continued to move with almost permanent sinusoidal forms. Ripple tank experiments are appropriate as laboratory work for an undergraduate course as well as for a demonstration of the nature of waves in an elementary physics course.