@physletName|EField
@code|eField4.EField.class
@archive|EField4_.jar,STools4.jar
@appletSize|250|250
@embedParam|b|ShowControls|false|show controls:
@embedParam|i|FPS|10|animation frames per second:
@embedParam|d|Dt|0.02|time step per frame:
@embedParam|b|PointChargeMode|true| point charge force law:
@embedParam|b|ShowContours|true|show potential contours:
@embedParam|b|ShowFieldVectors|true|show vector field:
@embedParam|b|ShowFieldLines|false|show vector lines:
@embedParam|b|ShowLabels|false|show contour labels:
@embedParam|b|ShowCharge|true|show charges as circles:
@embedParam|s|Potential|0|the potential:
@embedParam|s|Range|-5,5,-5,5|the x and y scale:
@embedParam|i|GridSize|64|the grid size used to calcualate the contours:
addObject|id
#FF707D
>>> tt >>>
A static charge
at position x,y with charge q and mass m, display radius r (pixels)
>>> tt >>>
Add charge
s|name|charge|HIDDEN
$
.|d|x|0|x:
.|d|y|0|y:
.|d|q|1.0|q:
.|d|m|1.0|m:
.|i|r|10|r:
addObject|id
#FF707D
>>> tt >>>
A dynamic test charge
at position x,y with initial velocity vx, vy, charge q and mass m, display radius r (pixels)
It will move according to fields from static charges and potentials without influencing these external fields.
Motion takes place after "forward()" (see below) is invoked.
>>> tt >>>
Add test charge
s|name|testcharge|HIDDEN
$
.|d|x|1|x:
.|d|y|2|y:
.|d|vx||vx:
.|d|vy||vy:
.|d|q|1.0|q:
.|d|m|1.0|m:
.|i|r|5|r:
forward|
#E9D3FF
>>> tt >>>
Start the animation clock.
This is necessary before any object will move.
For other correspondent methods (pause, step forward...) see below
>>> tt >>>
forward
deleteObject|
#FF707D
>>> tt >>>
This deletes a single object from the running applet, after it has appeared for a while.
To remove an object totally, simply delete the correspondent line from the script below and press "Update".
>>> tt >>>
Delete
o|id||<- Please read information (i) first! Delete this object at run-time:
setBz|
#FF707D
>>> tt >>>
An external magnetic field perpendicular to the visible plain.
External fields affect the motion of test charges.
>>> tt >>>
Set Bz
d|bz|10|external field Bz:
setPotential|
#FF707D
>>> tt >>>
Change the external electric potential and scale from what was set with the embedding parameters. External fields affect the motion of test charges.
>>> tt >>>
Set potential
s|ps||ps:
d|xmin|-5.0|xmin:
d|xmax|5.0|xmax:
d|ymin|-5.0|ymin:
d|ymax|5.0|ymax:
setShowContours|
#FFDA92
>>> tt >>>
Show (default) or hide the contour lines.
For other methods of display options see below (scroll down).
>>> tt >>>
Show potential
b|sc|true|Show equipotential (contour) lines:
setShowFieldLines|
#FFDA92
>>> tt >>>
Show field lines.
Caution, may fail for external potentials with non-zero divergence!
- See field vectors.
- See below "Field line click" which displays one single field line per mouse click.
>>> tt >>>
Show field lines
b|sfl|true|Show field lines:
setShowFieldVectors|
#FFDA92
>>> tt >>>
Draw field vectors. The color of the arrows indicates the strength of the field.
For other methods of display options see below.
>>> tt >>>
Show field vectors
b|sfv|false|Show field vectors:
setShowFVector|
#FFDA92
>>> tt >>>
Show the force vector on a test charge.
For other methods of display options see below.
>>> tt >>>
F vector
o|id||This test charge:
b|sf|true|displays its force vector:
setShowVVector|
#FFDA92
>>> tt >>>
Show the velocity vector of a test charge.
For other methods of display options see below.
>>> tt >>>
v vector
o|id||This test charge:
b|sv|false|displays its velocity vector:
setDragable|
#FFFF99
>>> tt >>>
Make an object dragable with the mouse.
Dragable test charges will not move according to the field any longer.
Instead, the force acting on them can be displayed while dragging (see below)
>>> tt >>>
Make dragable
o|id||This object:
b|drag|true|can be dragged with the mouse:
setDampOnMousePressed|
#FFFF99
>>> tt >>>
Set the velocity of all test charges to zero when the mouse is pressed.
See below for setting a constant damping coefficent.
>>> tt >>>
Damp motion
b|damp|true|Damp motion on mouse pressed:
setTrajectory|
#FFFF99
>>> tt >>>
Fo