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.
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.
- Measure the speed of sound in various gases and under varying conditions (temperature and pressure).
- Measure the speed of sound in metals using Kundt's tube apparatus.
- Make a quantitative measurement of the Doppler effect by measuring and analyzing the wave spectrum generated
by a rotating sound source and that produced by a moving car.
- Design an experiment to break a wine glass using sound waves.
- Make a high precision measurement of the speed of light using several methods. One will use Fizeau's rotating
mirror experiment and the other will use electronic techniques to measure the speed of light pulses in a coaxial
cable and in a plastic light guide.
- Use interferometry (Michelson, Fabry-Perot, Twyman-Green) to measure the index of refraction of air as a
function of gas pressure and temperature, the index of refraction of glass, and to study distortion in optical
components such as lenses.
- Use lasers in a variety of applications, such as light scattering from ordered and disordered systems,
measurement of refractive indices, or measurement of fluorescence in biochemical substances.
| 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.