trunk/multipole/PointCharges.py

#!/opt/local/bin/python2.7

'''An example script that generates a picture of the field lines for an electric dipole.'''

import math
import VectorFieldPlot as vfp


# create a document. we specify the file name and image size here
doc = vfp.FieldplotDocument( 'PointCharges', width=800,height=600,unit=100)

# create a field opbject
field = vfp.Field()
# add the point charges
field.add_element('monopoles' , [ [ 1,0, 1]  # the positive charge
                                , [-1,0,-1]  # the negative charge
                                ] )

# draw the charges for the field on the document
doc.draw_charges(field)

# start drawing the field lines
# we are going to draw 20 field lines comming off of the positive charge at uniformly spaced angles.
N = 20
for i in range(N):
    # compute the angle that the line will start off at
    angle = i * 2.*math.pi / (N-1)
    # generate the line
    # this takes the initial position, the x and y components of the initial direction, and whether or not should go forward
    # or backward.
    line = vfp.FieldLine( field, [1,0], start_v=[math.cos( angle ) , math.sin( angle )],directions='forward' )
    # draw the lin on the document
    doc.draw_line(line,arrows_style={'min_arrows':1,'scale':0.4,'max_arrows':3})

# write the document
doc.write()
Revision:	4407
Committed:	Wed Mar 30 17:58:47 2016 UTC (9 years, 7 months ago) by gezelter
Content type:	text/x-python
File size:	1301 byte(s)
Log Message:	Added some scripts to produce field line figures for the schematic
#	User	Rev	Content
1	gezelter	4407	#!/opt/local/bin/python2.7
2
3			'''An example script that generates a picture of the field lines for an electric dipole.'''
4
5			import math
6			import VectorFieldPlot as vfp
7
8
9			# create a document. we specify the file name and image size here
10			doc = vfp.FieldplotDocument( 'PointCharges', width=800,height=600,unit=100)
11
12			# create a field opbject
13			field = vfp.Field()
14			# add the point charges
15			field.add_element('monopoles' , [ [ 1,0, 1] # the positive charge
16			, [-1,0,-1] # the negative charge
17			] )
18
19			# draw the charges for the field on the document
20			doc.draw_charges(field)
21
22			# start drawing the field lines
23			# we are going to draw 20 field lines comming off of the positive charge at uniformly spaced angles.
24			N = 20
25			for i in range(N):
26			# compute the angle that the line will start off at
27			angle = i * 2.*math.pi / (N-1)
28			# generate the line
29			# this takes the initial position, the x and y components of the initial direction, and whether or not should go forward
30			# or backward.
31			line = vfp.FieldLine( field, [1,0], start_v=[math.cos( angle ) , math.sin( angle )],directions='forward' )
32			# draw the lin on the document
33			doc.draw_line(line,arrows_style={'min_arrows':1,'scale':0.4,'max_arrows':3})
34
35			# write the document
36			doc.write()