Physics Project 2009

Investigation of experiments and demonstrations in physics for incorporation into the middle and high school curricula

Faculty Mentor - Thomas Meyer, Vladimir Gasparayan

There will be one major change in our proposed program compared to the last two years. Last year we added one new acoustics experiment, which used Kundt's Tube to measure the speed of sound in metals.

Kundt's Tube Apparatus consists of a 90 cm long, 1 in diameter glass tube and an 81 cm aluminum rod. The rod is clamped at its center, while about 10 cm of it extends into the glass tube. A ¾ in disk is attached to the end of the rod to serve as a piston and effectively close off the tube, the other end being closed by a stopper. When the free end of the aluminum rod is stroked with a piece of rosined leather, a high pitched sound is produced by the vibration of the other and freely swinging end of the rod. This in turn produces standing waves in the air of the glass tube. When a thin layer of cork dust is placed in the tube, the dust collects in heaps indicating the nodes and antinodes of a standing wave produced in the tube. The distance between the nodes and the known speed of sound in air allow the measurement of the speed of sound in aluminum.

During last year's Chevron REVS-UP program Dr. Vladimir Gasparyan, myself and our team of high school students and teachers also observed striations, or fingerlike extensions from the cork dust (see below). These striations have been observed in Kundt's original experiment and Lord Raleigh wrote a theoretical paper about them in 1883. However, it seems that they have not been studied systematically and with modern experimental techniques.

{striations}

To this end we already have replaced the aluminum rod with the diaphragm of a loudspeaker driven by a sine wave generator and an amplifier. This setup allows us to vary the amplitude and frequency of the standing waves in the tube. We propose to study the properties of the striations as a function of frequency and various types and sizes of tubes. We also want to utilize other materials besides cork dust to see if the grain size of the dust effects the distance between the striations. Our ultimate goal is to find out the physical cause for the effect, which is not known, and formulate a theoretical model or theory to explain it.

In addition, our programs will continue to develop experiments and demonstrations appropriate for high schools and middle schools, which then could be taken back to the schools by participating teachers. All projects will be open-ended, i.e. participants will be able to work on the projects and develop new ones as they obtain results, or they will be able to improve on the experimental techniques to obtain better results.

1) Acoustics. This is similar to the program we ran the last two years. It focuses on a subject typically not covered in high school or college curricula. All experiments are exploratory, i.e. no specific instructions were given. Participants had to study the underlying physics, had to develop the experimental technique and then designed the experiments. Four experiments are proposed:

2) Optics and Lasers. The Physics, i.e. wave physics, is similar to that of acoustics. This will allow a comprehensive treatment of the theoretical physics required for both programs. Again, all experiments are exploratory, with no instructions given. Participants will have to study the underlying physics and then develop the experimental techniques appropriate for each experiment. We propose three general areas for experimental study.

Disclaimer

 These Web pages and any associated Adobe Acrobat Files are designed as supporting material for the respective projects. Please feel free to contact either of the program directors with any questions you might have.