@physletName|BField
@code|bfield.BField.class
@archive|BField4_.jar,STools4.jar
@appletSize|400|300
@scriptHeader|setAutoRefresh(false);
@scriptFooter|setAutoRefresh(true);
@embedParam|b|ShowControls|false|show controls:
@embedParam|s|Range|-5,5,-5,5|Range in units (use commas: "xmin,xmax,ymin,ymax")
@embedParam|i|GridSize|32|grid size:
addObject|wireID
#FF707D
>>> tt >>>
Add a straight wire perpendicular to the screen. Specify:
x - position of the center in world units
y - position of the center in world units
i - the current in the wire. Positive currents flow out of the screen.
>>> tt >>>
Add wire
s|name|wire|HIDDEN
$
.|d|x|0|x:
.|d|y|0|y:
.|d|i|1|current:
addObject|coilID
#FF707D
>>> tt >>>
Add a single circular conducting loop perpendicular to the screen. Specify:
x - position of the center in world units (see range in applet parameters)
y - position of the center in world units
r - the radius of the wire in world units
i - the current in the wire. Positive currents flow out of the screen.
>>> tt >>>
Add coil
s|name|coil|HIDDEN
$
.|d|x|1|x:
.|d|y|0|y:
.|i|r|1.5|r (units):
.|d|i|1|current:
addObject|compID
#FF707D
>>> tt >>>
Add a compass. Specify:
x - position of the center in world units
y - position of the center in world units
r - the radius of the compass in pixels
>>> tt >>>
Add compass
s|name|compass|HIDDEN
$
.|d|x|2|x:
.|d|y|2|y:
.|i|r|30|r (pixels):
addObject|shpID
#FFDA92
>>> tt >>>
Insert a shape and use their generated names "shp.." to change their properties with other commands
- circle - a filled circle lower left corner at (x,y)
specify: radius in pixels
- rectangle - a filled rectangle, centre at (x,y)
specify: height and width in pixels
- shell - a hollow circle, centre at (x,y)
specify: radius in pixels
- box - a hollow rectangle, centre at (x,y)
specify: radius in pixels
- box - a circle with cross hairs, centre at (x,y)
specify: height and width in pixels (and thickness of border in pixels - but this feature doesn't work yet)
>>> tt >>>
Add shape
s|type|circle;rectangle;shell;box;cursor|shape:
$
.|d|x|1|x:
.|d|y|0|y:
.|i|w||width:
.|i|h||heigth:
.|i|r||radius:
addObject|arwID
#FFDA92
>>> tt >>>
Arrows are often animation slaves of other objects.
>>> tt >>>
Add arrow
s|name|arrow|HIDDEN
$
.|d|x|1|x:
.|d|y|1|y:
.|s|h|1|horizontal:
.|s|v|1|vertical:
addObject|txtID
#FFDA92
>>> tt >>>
Add a text
x- double x position of the left side of the text in world units
y- double y position of the top of the text in world units
text- string static text.
calc- string An analytic function to be evaluated. The calculation is displayed to the right of the static text.
Text objects are often slaved to other objects. If a text object is slaved to an object, it takes on the properties of that object. In this Physlet, a slaved text object can evaluate a function of t, x, y, bx, by, i, curl, and path.
Note: The curl of the field is evaluated at the position, (x, y). The path is the line integral evaluated along the perimeter of a shell or a box object.
Note: To change the decimal format of the calculation use the setFormat method with the generated txt-variable as object.
>>> tt >>>
Add text
s|name|text|HIDDEN
$
.|d|x|0|x:
.|d|y|0.5|y:
.|s|text|your text|text:
.|s|calc||calculate:
addObject|imgID
#FFDA92
>>> tt >>>
An image file.
>>> tt >>>
Add image
s|name|image|HIDDEN
$
.|d|x|3|x:
.|d|y|0.5|y:
.|s|file|smile.gif|file:
addObject|capID
#FFDA92
>>> tt >>>
A caption is text that is centered near the top of the screen. Specify:
x- double x position of the center in world units
y- double y position of the center in world units
text- string text of the caption
Use the generated cap-Variable as object for "change color"
>>> tt >>>
Title
s|name|caption|HIDDEN
$
.|d|x|1|x:
.|d|y|-0.5|y:
.|s|text|your title|text:
setDefault|
#FF707D
>>> tt >>>
Deletes all objects during runtime. Use this at the begin of a new function (for a new button).
Tip: Place a #-sign at the top of the script field, before clicking on "Set default". The new command line will then go there instead of at the end of the function.
THIS METHOD IS NOT MEANT for correcting the script in this scriptor:
Just delete lines like "document.Animator1.addObject(..." by hand!
Beware: This will also do the following:
- deletes all data connections!
- sets some parameters into a predefined state.
(If this is not what you want, reset these values hereafter)
>>> tt >>>
Set default
setDragable|
#FFFF99
>>> tt >>>
Make an object relocatable with the mouse. Use the id (variable) returned by the add methods to identify the object you wish to change.
Parameters:
id - the object identifier
drag - true if dragable
Returns:
true if successful
>>> tt >>>
Set dragable
o|id||This object
b|drag|true|is dragable:
setResizable|
#FFFF99
>>> tt >>>
Make an object resizable. A resizable object will usually change its physical properites. For example, a resizable lens will change
its focal length.
Parameters:
id - the object identifier.
resizable - property
Returns:
true if successful.
>>> tt >>>
Set resizable
o|id||This object
b|isResizable|true|is resizable:
setVisibility|
#FFFF99
>>> tt >>>
Makes an object visible or invisible. The object is not destroyed; it is hidden and can be made visible at any time.
>>> tt >>>
Show/Hide
o|id||This object
b|show|false|is visible:
setAnimationSlave|
#FFFF99
>>> tt >>>
Combine a master object and a slave object so that the slave follows the master.
Slave could be a text - often in combination with a "display offset" for the text (see below)
>>> tt >>>
Animation Slave
o|masterID||master object:
o|slaveID||following object:
addObject|constrID
#FFFF70
>>> tt >>>
Specify a region to which other objects can be bound. Then use the newly generated ID "constr.." in a setContraint() command to apply this restriction to an object.
>>> tt >>>
Constraint region
s|name|constraint|HIDDEN
$
.|d|xmin||xmin:
.|d|xmax||xmax:
.|d|ymin||ymin:
.|d|ymax||ymax:
setConstraint|
#FFFF70
>>> tt >>>
Restrict the possible movements of an object to a region.
This region must previously be specified as a "constraint" in a separate command.
>>> tt >>>
Restrict motion
o|id||This object
o|constraintid||is restricted by this constraint (as defined above):
setShowFieldVectors|
#CCFFCC
>>> tt >>>
Show the direction field.
>>> tt >>>
Display field vectors
b|sfv|true|show field vectors:
setShowFieldLineOnDoubleClick|
#CCFFCC
>>> tt >>>
Enable the user to double click in order to draw a magnetic field line.
>>> tt >>>
Field line doubleclick
b|sfl|true|show a field line on double click:
setShowFVector|
#CCFFCC
>>> tt >>>
Enable a wire to show the net force vector acting on it.
>>> tt >>>
Show F vector
o|id||This object
b|showForce|true|shows a force vector:
setShowBOnDrag|
#CCFFCC
>>> tt >>>
Enable a the user to read the magnetic field magnitude by click-dragging the mouse.
>>> tt >>>
Display B
b|sb|true|Show B value on drag:
setShowCoordOnDrag|
#CCFFCC
>>> tt >>>
Enable a the user to read coordinates by click-dragging the mouse.
>>> tt >>>
Display x,y
b|sc|true|Mouse coordinates are displayed:
setShowForce|
#CCFFCC
>>> tt >>>
Show the absolute value of the force of a dragable object (in yellow box, behind the coordinates). Default: true
>>> tt >>>
Display F
o|id||This object
b|showForce|false|displays its force value:
setShowInfo|
#CCFFCC
>>> tt >>>
Enable a dragable object to show information such as the current on drag
>>> tt >>>
Display info
o|id||This object
b|showInfo|true|displays info on drag:
setSketchMode|
#CCFFCC
>>> tt >>>
Enable sketching with the mouse.
>>> tt >>>
Sketch mode
b|sketch|true|Users can draw sketches with mouse in applet:
setDisplayOffset|
#B3EFFF
>>> tt >>>
Offset the object's position on the screen from its default drawing
position.
>>> tt >>>
Display offset
o|id||For This object
i|xOff|20|xo:
i|yOff|20|yo:
swapZOrder|
#B3EFFF
>>> tt >>>
Swap the drawing order on the screen.
>>> tt >>>
Foreground/ Background
o|id1||This object:
o|id2||swaps z-order with this object:
setObjectFont|
#B3EFFF
>>> tt >>>
change the object's font for any text that is displayed.
>>> tt >>>
Object font
o|id||For this text object:
s|family||font family:
i|style|20|style:
i|size|20|size:
setRGB|
#B3EFFF
>>> tt >>>
Set the red, green, and blue color values for a wire or coil that has already been created.
>>> tt >>>
Color
o|id||This object
i|r|255|has color components r:
i|g|0|g:
i|b|0|b:
getBx|bx
#E9D3FF
>>> tt >>>
Get the x component of the B field at a point.
>>> tt >>>
Get Bx
d|x|0|x:
d|y|0|y:
getBy|by
#E9D3FF
>>> tt >>>
Get the y component of the B field at a point.
>>> tt >>>
Get By
d|x|0|x:
d|y|0|y:
setCurrent|
#FF707D
>>> tt >>>
Change the current of a wire or loop after it has been created.
This can be performed by sliders.
>>> tt >>>
Set I
o|id||This object
d|c|-1|has current I:
setBFunctions|
#FF707D
>>> tt >>>
Set an external magnetic field in a rectangular array
>>> tt >>>
Set B
s|bx||Bx(x,y):
s|by||By(x,y):
d|xmin|-1|xmin:
d|xmax|1|xmax:
d|ymin|-1|ymin:
d|ymax|1|ymax:
setRadius|
#FF707D
>>> tt >>>
Change the radius (in world units) of a loop after it has been created.
>>> tt >>>
Set r
o|id||This object
d|r|1|has radius r:
setXY|
#FF707D
>>> tt >>>
Set position of an object.
>>> tt >>>
Set x,y
o|id||This object
d|x|0|has coordinates x:
d|y|0|y:
reset|
#FFFFFF
>>> tt >>>
Reset the applet and clear the field lines.
>>> tt >>>
Reset