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from visual import *
print """
Click to plot a normalized electric field vector.
Vectors are blue if low magnitude, red if high.
Right button drag to rotate camera to view scene.
Middle button drag up or down to zoom in or out.
"""
ec = 1.6e-19 # electron charge
charges = [ sphere( pos = (-1e-13,0,0), Q = ec, color=color.red, radius = 6e-15 ),
sphere( pos = ( 1e-13,0,0), Q = -ec, color=color.blue, radius = 6e-15 ),
]
scene.title="Electric Field Vectors"
scene.range = 2e-13
def getfield(p):
f = vector(0,0,0)
for c in charges:
f = f + (p-c.pos) * 8.988e9 * c.Q / mag(p-c.pos)**3
return f
while 1:
p = scene.mouse.getclick().pos
f = getfield(p)
m = mag(f)
red = maximum( 1-1e17/m, 0 )
blue = minimum( 1e17/m, 1 )
if red >= blue:
blue = blue/red
red = 1.0
else:
red = red/blue
blue = 1.0
arrow( pos=p, axis=f * (4e-14/1e17),
shaftwidth = 6e-15,
color=(red,0,blue))
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