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Faraday AddObject Method

Faraday allows the creation of wire loops, geometric shapes, and text as well as the default "U" shaped wire.

addObject(String name, String attributes)

Objects usually, but not always, have an on-screen representation.  The first argument is the name of the object to be added, and the second is a comma-delimited list of parameters.  A circle can now be added to either applet using the following JavaScript statement:

document.physletname.addObject("circle", "x=0,y=-1.0,r=10");.

The addObject method is very forgiving since not all parameters need to be specified.  Default values are overridden only if the parameter appears in the list.  Incorrect and unsupported parameters do not affect the applet and are ignored.

The table below lists the name and the associated parameters for version 4 of the BField Physlet.   Consult the online documentation for information about other Physlets.  OpticsBench, for example, supports the addObject method for lenses, mirrors, and light sources.

Name  Attributes
arrow

Arrows are often animation slaves of other objects.  They can represent almost any vector since the h and v components can be functions of the variables.

x- double position of the base in world units
y- double position of the base in world units.
h- string horizontal component
v- string vertical component
s -int size of arrowhead
box

A hollow rectangle.

 

x- double position of the base in world units
y- double position of the base in world units.
h- int height in pixels
w- int width in pixels
caption

Text.

x- double position of the base in world units
y- double position of the base in world units.
txt- string text
constraint

A constraint on dragged objects.

 

xmin- double minimum x
xmax- double maximum x
ymin- double minimum y
ymax- double maximum y
circle

A filled circle.

x- double position of the base in world units
y- double position of the base in world units.
r- int radius in pixels
coil

A current carrying coil.

 

x- double position of the base in world units
y- double position of the base in world units.
i- double current
r- int coil radius
s- int size
cursor

A circle with crosshairs

x- double position of the base in world units
y- double position of the base in world units.
r- int radius in pixels
image

A gif image.

x- double position of the base in world units
y- double position of the base in world units.
file- string image file relative to code base
rectangle

A filled rectangle.

x- double position of the base in world units
y- double position of the base in world units.
h- int height in pixels
w- int width in pixels
shell

A hollow circle.

x- double position of the base in world units
y- double position of the base in world units.
r- int radius in pixels
text

A text message with an optional calculation.

 

x- double position of the base in world units
y- double position of the base in world units.
txt- string message
calc- string an analytic function that is appended to the message.

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.

Use the setFormat method described to change the decimal format used to output the calculation.
uwire

A "U" shaped current carrying wire.

x- double position of the slide wire that connects the two arms of the "U" in world units