File:VFPt metal balls largesmall transparent.svg
Page contents not supported in other languages.
Tools
Actions
General
In other projects
Appearance
![File:VFPt metal balls largesmall transparent.svg](http://upload.wikimedia.org/wikipedia/commons/thumb/a/af/VFPt_metal_balls_largesmall_transparent.svg/800px-VFPt_metal_balls_largesmall_transparent.svg.png)
Size of this PNG preview of this SVG file: 800 × 600 pixels. Other resolutions: 320 × 240 pixels | 640 × 480 pixels | 1,024 × 768 pixels | 1,280 × 960 pixels | 2,560 × 1,920 pixels.
Original file (SVG file, nominally 800 × 600 pixels, file size: 41 KB)
![]() | This is a file from the Wikimedia Commons. Information from its description page there is shown below. Commons is a freely licensed media file repository. You can help. |
Summary
DescriptionVFPt metal balls largesmall transparent.svg |
English: Electric field around a large and a small conducting sphere at opposite electric potential. The shape of the field lines is computed exactly, using the method of image charges with an infinite series of charges inside the two spheres, shown in red and blue. In reality, the field is created by a continuous charge distribution at the surface of each sphere and the field lines inside the sphere don't exist. Field lines are always orthogonal to the surface of each sphere. |
Date | |
Source | Own work |
Author | Geek3 |
Other versions |
|
SVG development InfoField | |
Source code InfoField | Python code# paste this code at the end of VectorFieldPlot 1.10
# https://commons.wikimedia.org/wiki/User:Geek3/VectorFieldPlot
u = 100.0
doc = FieldplotDocument('VFPt_metal_balls_largesmall_transparent',
commons=True, width=800, height=600, center=[400, 300], unit=u)
# define two spheres with position, radius and charge
s1 = {'p':sc.array([-1.0, 0.]), 'r':1.5}
s2 = {'p':sc.array([2.0, 0.]), 'r':0.5}
# make charge proportional to capacitance, which is proportional to radius.
s1['q'] = s1['r']
s2['q'] = -s2['r']
d = vabs(s2['p'] - s1['p'])
v12 = (s2['p'] - s1['p']) / d
# compute series of charges https://dx.doi.org/10.2174/1874183500902010032
charges = [[s1['p'][0], s1['p'][1], s1['q']], [s2['p'][0], s2['p'][1], s2['q']]]
r1 = r2 = 0.
q1, q2 = s1['q'], s2['q']
q0 = max(fabs(q1), fabs(q2))
for i in range(10):
q1, q2 = -s1['r'] * q2 / (d - r2), -s2['r'] * q1 / (d - r1),
r1, r2 = s1['r']**2 / (d - r2), s2['r']**2 / (d - r1)
p1, p2 = s1['p'] + r1 * v12, s2['p'] - r2 * v12
charges.append([p1[0], p1[1], q1])
charges.append([p2[0], p2[1], q2])
if max(fabs(q1), fabs(q2)) < 1e-3 * q0:
break
field = Field({'monopoles':charges})
# draw symbols
for c in charges:
doc.draw_charges(Field({'monopoles':[c]}), scale=0.6*sqrt(fabs(c[2])))
gradr = doc.draw_object('linearGradient', {'id':'rod_shade', 'x1':0, 'x2':0,
'y1':0, 'y2':1, 'gradientUnits':'objectBoundingBox'}, group=doc.defs)
for col, of in (('#666', 0), ('#ddd', 0.6), ('#fff', 0.7), ('#ccc', 0.75),
('#888', 1)):
doc.draw_object('stop', {'offset':of, 'stop-color':col}, group=gradr)
gradb = doc.draw_object('radialGradient', {'id':'metal_spot', 'cx':'0.53',
'cy':'0.54', 'r':'0.55', 'fx':'0.65', 'fy':'0.7',
'gradientUnits':'objectBoundingBox'}, group=doc.defs)
for col, of in (('#fff', 0), ('#e7e7e7', 0.15), ('#ddd', 0.25),
('#aaa', 0.7), ('#888', 0.9), ('#666', 1)):
doc.draw_object('stop', {'offset':of, 'stop-color':col}, group=gradb)
ball_charges = []
for ib in range(2):
ball = doc.draw_object('g', {'id':'metal_ball{:}'.format(ib+1),
'transform':'translate({:.3f},{:.3f})'.format(*([s1, s2][ib]['p'])),
'style':'fill:none; stroke:#000;stroke-linecap:square', 'opacity':0.5})
# draw rods
if ib == 0:
x1, x2 = -4.1 - s1['p'][0], -0.9 * s1['r']
else:
x1, x2 = 0.9 * s2['r'], 4.1 - s2['p'][0]
doc.draw_object('rect', {'x':x1, 'width':x2-x1,
'y':-0.1/1.2+0.01, 'height':0.2/1.2-0.02,
'style':'fill:url(#rod_shade); stroke-width:0.02'}, group=ball)
# draw metal balls
doc.draw_object('circle', {'cx':0, 'cy':0, 'r':[s1, s2][ib]['r'],
'style':'fill:url(#metal_spot); stroke-width:0.02'}, group=ball)
ball_charges.append(doc.draw_object('g',
{'style':'stroke-width:0.02'}, group=ball))
# find well-distributed start positions of field lines
def get_startpoint_function(startpath, field):
'''
Given a vector function startpath(t), this will return a new
function such that the scalar parameter t in [0,1] progresses
indirectly proportional to the orthogonal field strength.
'''
def dstartpath(t):
return (startpath(t+1e-6) - startpath(t-1e-6)) / 2e-6
def FieldSum(t0, t1):
return ig.quad(lambda t: sc.absolute(sc.cross(
field.F(startpath(t)), dstartpath(t))), t0, t1)[0]
Ftotal = FieldSum(0, 1)
def startpos(s):
t = op.brentq(lambda t: FieldSum(0, t) / Ftotal - s, 0, 1)
return startpath(t)
return startpos
startp = []
def startpath1(t):
phi = 2. * pi * t
return (sc.array(s2['p']) + 1.5 * sc.array([cos(phi), sin(phi)]))
start_func1 = get_startpoint_function(startpath1, field)
nlines1 = 16
for i in range(nlines1):
startp.append(start_func1((0.5 + i) / nlines1))
def startpath2(t):
phi = 2. * pi * (0.195 + 0.61 * t)
return (sc.array(s1['p']) + 1.5 * sc.array([cos(phi), -sin(phi)]))
start_func2 = get_startpoint_function(startpath2, field)
nlines2 = 14
for i in range(nlines2):
startp.append(start_func2((0.5 + i) / nlines2))
# draw the field lines
for p0 in startp:
line = FieldLine(field, p0, directions='both', maxr=7.)
arrow_d = 2.0
of = [0.5 + s1['r'] / arrow_d, 0.5, 0.5, 0.5 + s2['r'] / arrow_d]
doc.draw_line(line, arrows_style={'dist':arrow_d, 'offsets':of})
doc.write()
|
Licensing
I, the copyright holder of this work, hereby publish it under the following license:
![w:en:Creative Commons](https://upload.wikimedia.org/wikipedia/commons/thumb/7/79/CC_some_rights_reserved.svg/90px-CC_some_rights_reserved.svg.png)
![attribution](https://upload.wikimedia.org/wikipedia/commons/thumb/1/11/Cc-by_new_white.svg/24px-Cc-by_new_white.svg.png)
![share alike](https://upload.wikimedia.org/wikipedia/commons/thumb/d/df/Cc-sa_white.svg/24px-Cc-sa_white.svg.png)
This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International license.
- You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
- Under the following conditions:
- attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
- share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
Captions
Add a one-line explanation of what this file represents
Items portrayed in this file
depicts
30 December 2018
image/svg+xml
File history
Click on a date/time to view the file as it appeared at that time.
Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 20:05, 30 December 2018 | ![]() | 800 × 600 (41 KB) | Geek3 | User created page with UploadWizard |
File usage
The following pages on the English Wikipedia use this file (pages on other projects are not listed):
Global file usage
The following other wikis use this file:
- Usage on es.wikipedia.org
Metadata
This file contains additional information, probably added from the digital camera or scanner used to create or digitize it.
If the file has been modified from its original state, some details may not fully reflect the modified file.
Short title | VFPt_metal_balls_largesmall_transparent |
---|---|
Image title | VFPt_metal_balls_largesmall_transparent
created with VectorFieldPlot 1.10 https://commons.wikimedia.org/wiki/User:Geek3/VectorFieldPlot about: https://commons.wikimedia.org/wiki/File:VFPt_metal_balls_largesmall_transparent.svg rights: Creative Commons Attribution ShareAlike 4.0 |
Width | 800 |
Height | 600 |