| Product Name: |
ChgDist |
| Level: |
a Year 12 class/ First Year Tertiary |
| Platform: |
PC - DOS |
| Supplied Information: |
ChgDist is a stand alone simulation which shows how charges redistribute themselves over a surface of a material through which they can move freely. The program is written in Turbo Pascal using the MUPPET utilities. Download from ftp.physics.usyd.edu.au/pub/walker |
| Possible Use: |
This product is suitable for a Year 12 class/ First Year Tertiary courses for use by teachers during lecture classes. |
| Price: |
Freeware |
| Developer/s: |
Dr P J Walker & A/Prof I D Johnston |
| Review: |
This software package addresses the assumptions, and their philosophical difficulties, associated with understanding both as to why free charges reside only on the outside of a conductor and as to why it concentrates at regions of high surface curvature. The pedagogical approach relies on first principles charge repulsion, side stepping Gauss's Law for conceptually difficult reasons; which difficulties are often experienced by students. The results are illuminating and may be used to underpin subsequent instruction using Gauss's Law to achine similar ends (Refer: P J Walker & I D Johnston, "Computer Model Clarifies Spontaneous Charge Distribution in Conductors", Computers In physics, 9 (1), 1995, PP 43-45). The prgramme begins with randomly mouse-positioning a number of equal charges on screen within a chosen boundary surface (a contour on the 2D screen also drawn by mouse). Short fiducial lines attached to each charge (shown as a dot) indicate the local force vector direction due to all of the other charges. The charges mutually repel and eventually reach the chosen contour where they are constrained so as to be able only to move along the contour. The impressive on-screen result shows the charges migrating so as to concentrate at regions of high contour curvature with their short line markers eventually all pointing perpendicular to the local contour tangent, giving the direction of the local electric field. The program also has the facility to plot the electric field at co-ordinates external to the contour and to plot equipotential contours. The operation of the programme is easy and the results most instructive and informative given that only simple Coulomb repulsion is invoked at all stages of the motion of the charges. The screen is easily video projected for teaching purposes and teh above process is stepped through quite quickly in terms of a teaching period time frame. Overall, the demonstration is simple and very elegant. Highly recommended. |
|
J Liesegang, La Trobe University, phyjl@luxor.latrobe.edu.au |
Other references
to this product: |
P J Walker & I D Johnston, Computers In physics, 9 (1), 1995, PP 43-45 |
| |
| Date Record Last Modified: |
12/6/97 |
