Summary

{{Information

|description=

|date=2018-12-15 |source=Own work |author=Geek3 |permission= |other versions= |other fields={{Igen|VectorFieldPlot|0|+|%v|^|c1=

1. paste this code at the end of VectorFieldPlot 3.1
2. https://commons.wikimedia.org/wiki/User:Geek3/VectorFieldPlot

doc = FieldplotDocument('VFPt_ringmagnet2',

   commons=True, width=600, height=600)

r0 = 1.0 r1 = 2.0 h = 0.5 field = Field([ ['coil', {'x':0, 'y':0, 'phi':pi/2, 'R':r1, 'Lhalf':h, 'I':1}],

        ['coil', {'x':0, 'y':0, 'phi':pi/2, 'R':r0, 'Lhalf':h, 'I':-1}] ])

n_out = 24 for i in range(n_out):

   s = (i + 0.5) / n_out * 2. - 1.
   line = FieldLine(field, [copysign(r1 + h * (1. / s**2 - 1.), s), 0.],
       directions='both', maxr=1e3)
   doc.draw_line(line, linewidth=2.4, arrows_style={'scale':1.1,
       'potential':lambda xy: xy[1] * (1-fabs(xy[0]/2.5)**2.5-fabs(xy[1]/2)**2.5),
       'at_potentials':[0], 'condition_func':lambda xy: fabs(xy[1]) > 0.7 or
           (fabs(xy[0]) > r1 and fabs(xy[1]) < 1e-4)})

n_in = 12 for i in range(n_in):

   a = (i + 0.5) / n_in * 2. - 1.
   line = FieldLine(field, [r0 * (1.2*a - 0.2*a**3), 0.],
       directions='both')
   doc.draw_line(line, linewidth=2.4, arrows_style={'scale':1.1,
       'potential':lambda xy: xy[1], 'at_potentials':[0],
       'condition_func':lambda xy: fabs(xy[0]) < r0})

1. draw the magnet manually

colors = ['#00cc00', '#ff0000'] defs = doc.draw_object('defs', {}) grad = doc.draw_object('linearGradient', {'id':'grad',

   'x1':str(r0), 'x2':str(-r0), 'y1':'0', 'y2':'0',
   'gradientUnits':'userSpaceOnUse'}, group=defs)

for col, of, opa in [['#000000', '0', '0.125'],

   ['#ffffff', '0.07', '0.125'], ['#ffffff', '0.25', '0.5'],
   ['#ffffff', '0.6', '0.2'], ['#000000', '1', '0.33']]:
   stop = doc.draw_object('stop', {'stop-color':col, 'offset':of,
       'stop-opacity':opa}, group=grad)

mag = doc.draw_object('g', {'id':'magnet'}, bg=True) for i in [0, 1]:

   rect = doc.draw_object('rect', group=mag)
   for attr, val in [['x', -r0], ['y', [-h, 0][i]],
       ['width', 2*r0], ['height', [2*h, h][i]],
       ['style', 'fill:{0}; stroke:none'.format(colors[i])]]:
       rect.set(attr, str(val))

rect = doc.draw_object('rect', group=mag) for attr, val in [['x', -r0], ['y', -h],

   ['width', 2 * r0], ['height', 2 * h],
   ['style', 'fill:url(#grad); stroke-width:0.04; stroke-linejoin:miter; stroke:#000000']]:
   rect.set(attr, str(val))

for x0 in [-r1, r0]:

   mag = doc.draw_object('g')
   for i in [0, 1]:
       rect = doc.draw_object('rect', group=mag)
       for attr, val in [['x', x0], ['y', [-h, 0][i]],
           ['width', r1 - r0], ['height', [2*h, h][i]],
           ['style', 'fill:{0}; stroke:none'.format(
           ['#49da49', '#ff4949'][i])]]:
           rect.set(attr, str(val))
   rect = doc.draw_object('rect', group=mag)
   for attr, val in [['x', x0], ['y', -h],
       ['width', r1 - r0], ['height', 2 * h],
       ['style', 'fill:none; stroke-width:0.04; stroke-linejoin:miter; stroke:#000000']]:
       rect.set(attr, str(val))

doc.write() }} }}

Licensing

I, the copyright holder of this work, hereby publish it under the following license:

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You are free:

• to share – to copy, distribute and transmit the work
• to remix – to adapt the work

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• 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.

https://creativecommons.org/licenses/by-sa/4.0CC BY-SA 4.0 Creative Commons Attribution-Share Alike 4.0 truetrue

Category:CC-BY-SA-4.0#VFPt%20ringmagnet2.svg