Development of a Web-based Learning System at the Institut Teknologi BandungR. Soegeng
Department of Physics, Institut Teknologi Bandung, Indonesia
Realizing that most of our students experience difficulties in understanding basic sciences which are full of abstract concepts, Institut Teknologi Bandung has begun to look at the use of the Web in the process of learning. From the beginning we have tried to develop a prototype of a web-based learning package which was then uploaded to the Common First Year Program web site. We call it a prototype because this is our first experience in web-based learning.
One of the packages, which comes from the Department of Physics, discusses the properties of mechanical waves. The main purpose of the package is to show the students visualization of the properties of waves to support the lecture. These are not covered in the classroom, because there is not enough equipment, such as computers, projectors, film, etc.
The discussion begins with an explanation that there are two kinds of waves, these are electromagnetic waves and mechanical waves. Furthermore, mechanical waves consist of transverse and longitudinal waves, depending on the direction of oscillation of particles of the medium relative to the direction of propagation of the waves. Visualization of these waves clearly shows the direction of oscillation of particles of the medium, so that students can easily understand the difference between those waves.
Next, the package discusses the wave equation. Serious students may follow the derivation of the formula for propagation along a string, propagation in a rod, and propagation of sound in air. This discussion is followed by a representation of wave function as a solution of the wave equation. The package does not include the derivation of the wave function because it is discussed at length in the classroom.
Following the discussion on the wave equation and the wave function, the package represents one and two dimensional waves. Examples of those waves are a wave that propagates along an infinite string, a line wave that propagates on an unbounded membrane, a circular wave that propagates also on an unbounded membrane, and a surface wave on a very large pond. Students who want to know the form of the path followed by the particles of water can also find the derivation of the formula in the package.
While the above discussions and visualizations are limited to single waves that propagate along an unbounded medium, the subsequent discussion covers the superposition of two waves. This section is divided into two sub-sections. The first sub-section discusses superposition of two waves with a common plane of vibration. There are three visualizations in this discussion each followed by an explanation of the mechanism of wave superposition; superposition in general, standing waves and beats. The second sub-section discusses polarization, where the planes of vibration of the waves are perpendicular to each other. This sub-section also includes analysis of properties of the resulting wave. The visualization of polarization also includes projection on a plane perpendicular to the direction of propagation, so that students can easily understand what is meant by left or right polarized wave.
In the last discussion the package shows what happens when a wave propagates along a limited medium. For example, what happens if a wave propagates along a string and then comes to a junction with another string with different properties? or ultimately, what happens if a wave propagates along a string and then comes to the end of the string? There are two possibilities for the end of the string. It may be free, or it may be fixed. In the package each situation is analyzed mathematically and also shown in a visualization.
Each visualization in the package has been made as interactive as possible, and an easy to read explanation enables students to change the parameters of the wave or the medium and watch what happens to the wave. In this way we hope that students will enjoy physics more than before. The text in the package was written in MS Word and saved as HTML files, illustrations were made with Corel Draw, and visualizations were prepared with Delphi (Thank you Professor Ian Johnston for your suggestion to use Delphi).
UniServe Science News Volume 16 July 2000
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