The program currently simulates three different types of charge distributions:

• randomly positioned "free" charges,
• symmetrically positioned "free" charges, and
• "bound" charges distributed on a variety of three-dimensional conducting surfaces.

In the first two modes, charges are free to move about in response to mutual electrostatic forces of attraction and repulsion. In the 3-D conductor mode, the simulation shows a cross-sectional view of a 3-D conductor, and all charges are constrained to move around on the surface of the conductor. (I originally planned to develop two other modes of operation, "On a 2D Conductor" and "Inside a Dielectric," but these plans had to be on hold.) The "Conductor Shape:" pull-down menu lists four different geometries (dumbbell, ellipse, line, and triangle). (Plans to implement two other geometries, "square" and "user-defined" were also put on hold.) The following descriptions briefly summarize the operation of each of the remaining control buttons and checkboxes.

• a toggle button which starts and stops animation

• a toggle which pauses and resumes animation
• only enabled when animation is running

• reverses the direction of time
• only enabled when animation is running

• used at end of an animation sequence to restore the charge distribution to its initial state
• used for "instant replay" of an interesting animation sequence

• redraws the screen using whatever viewing tools are currently selected
• used for switching between different viewing modes

• in "Random Free Charges" mode, generates a new group of randomly-placed charges
• in "Symmetric Free Charges" mode, selects the next symmetrical distribution in the sequence of 7 distributions

• in "Random Free Charges" mode, restores the previous random charge distribution
• in "Symmetric Free Charges" mode, selects the preceding symmetrical distribution

• disables screen clearing between animation frames for special effects
• causes charges to leave "trails" behind them during animation sequences
• looks pretty cool - try it!

• when selected, draws a vector showing the magnitude and direction of the electric field at the current location of the mouse cursor
• when used in conjunction with field lines, this vector shows the direction of the field lines and is always tangent to them

• when selected, shows the electrical potential at the current location of the mouse cursor as a point on a vertically sliding potential scale
• the height of the scale above the tip of the mouse cursor indicates the relative height of the electrical potential at that point
• red represents the highest (most positive) potential, violet the lowest (most negative) potential

• used to give charges an initial "kick" in preparation for animation
• to use this feature, position mouse cursor on the charge you want to "kick"
• click and hold left mouse button
• velocity direction and magnitude indicators will appear at the lower right hand side of the graphics screen
• drag mouse cursor outside of charge
• drag mouse cursor until the desired speed and angle (in degrees) are selected
• release left mouse button
• when animation starts, the charge will begin moving in the chosen direction with the chosen speed

• only used with 3D conductor distributions
• when selected, places a large positive charge at the location of the mouse cursor
• used to show how the surface charge distribution would change in response to the presence of a large external opposite charge

• when selected, shows positions of all charges
• by hiding the charges, the user can concentrate on changes in fields and potentials
• produces interesting animation effects when turned off

• when selected, draws field lines
• field lines are aesthetically pleasing and interesting, but take a long time to draw
• avoid turning on field lines when animating the charges - the animation will run very slowly if more than two or three charges are present

• when selected, draws equipotential lines
• lines are coordinated with the 20-color potential scale
• lines mark the boundaries between the colored potential ranges
• equipotential lines are aesthetically pleasing and interesting, but take a long time to draw
• avoid turning on equipotentials when animating the charges - the animation will run very slowly if more than two or three charges are present

• a "poor man's" attempt at 3D rendering
• when selected, shows positive charges as slight positive elevations, negative charges as slight depressions
• when animated, this viewing mode produces interesting visuals, particularly when "hills" and "valleys" collide and annihilate each other

• when selected, shows a field of "electrical compasses," i.e. vectors showing the local field direction
• when animated, this viewing mode produces interesting visuals, like wind blowing through a wheat field

• when selected, shows electrical potentials in a topological map format using a 20-color scale
• red represents the highest (most positive) potential, violet the lowest (most negative) potential
• when animated, this viewing mode produces interesting visuals, as blobs of color expand, contract, merge, and separate

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