File:VFPt sphere-magnet-inside.svg
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Original file (SVG file, nominally 600 × 600 pixels, file size: 30 KB)
Summary
| Description |
English: Drawing of a homogeneously magnetized spherical magnet with exactly computed magnetic field lines. A spherical magnet has the remarkable property that its field outside the magnet is identical to that of an ideal point-like dipole. Inside the magnetized volume, the field is exactly constant and aligned along the north-south axis. The shown B-field points straight from south to north inside the magnet, whereas the H-field, although identical to B in free space, would point from north to south inside the magnet. |
| Date | |
| Source | Own work |
| Author | Geek3 |
| Other versions |
 |
| SVG development | |
| Source code | Python code# paste this code at the end of VectorFieldPlot 3.3
doc = FieldplotDocument('VFPt_sphere-magnet-inside', commons=True,
width=600, height=600)
x0, y0 = 0.0, 0.0
R = 1.0
dipole_field = Field([ ['dipole', {'x':0, 'y':0, 'px':0, 'py':1}] ])
def spheremagnet_F(xy):
r = xy - sc.array((x0, y0))
if vabs(r) < R:
# inside the field is indeed constant
return dipole_field.F(sc.array((0, R)))
else:
# outside the field is exatly that of a point-dipole
return dipole_field.F(r)
field = Field([ ['custom', {'F':spheremagnet_F}] ])
nlines = 18
for iline in range(nlines):
p0 = (R * (2 * (iline + 0.5) / nlines - 1), 0.)
line = FieldLine(field, p0, directions='both', maxr=7)
doc.draw_line(line, arrows_style={'scale':1.2, 'at_potentials':[0],
'potential':lambda xy: xy[1] * (vabs(xy) - 2.3)})
# draw the spherical magnet
g = doc.draw_object('g', {'id':'sphere',
'transform':'translate({},{})'.format(x0, y0)}, bg=True)
doc.draw_object('circle', {'cx':'0', 'cy':'0', 'r':str(R),
'style':'fill:#80e680; stroke:none;'}, group=g)
doc.draw_object('path', {'d':'M -1,0 A 1,1 0 0 0 1,0 L -1,0 Z',
'style':'fill:#ff8080; stroke:none;'}, group=g)
doc.draw_object('circle', {'cx':'0', 'cy':'0', 'r':str(R),
'style':'fill:none; stroke:#000000; stroke-width:0.04;'}, group=g)
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
- 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.
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 13:10, 18 January 2021 | | 600 × 600 (30 KB) | wikimediacommons>Geek3 | less field lines. Arrows distributed in a circle |
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