I am trying to plot the electric field generated when an spheric conductor is placed in an homogeneous electric field. I based my code on this question to use np.where function to filter out the unitary circle. But instead of that, all of the field at -1< x<1 is filtered out.
My code is shown below, how can I fix this?
import sys
import numpy as np
import matplotlib.pyplot as plt
import scipy.constants as spc
def E(x, y):
"""due to an spheric conductor set on a homogeneous electric field"""
E_x = 3*x*y/((y**2+x**2)**2.5)
E_y = 3*y*y/((y**2+x**2)**2.5)-1/((y**2+x**2)**1.5)+1
return E_x, E_y
# Grid of x, y points
n= 100
a=2
y = np.linspace(-a, a, n)
x = np.linspace(-a, a, n)
X, Y = np.meshgrid(x, y)
r=(x**2+y**2)**0.5
circle = r>=1
Ex, Ey = E(X,Y)
Ex, Ey = np.where(circle,Ex,0), np.where(circle,Ey,0)
#plot
fig = plt.figure()
ax = fig.add_subplot(111)
color = 2 * np.log(np.hypot(Ex, Ey))
ax.streamplot(x, y, Ex, Ey, color=color, linewidth=1, cmap=plt.cm.inferno,
density=1, arrowstyle='->', arrowsize=1.5)
ax.set_ylabel('$y$')
ax.set_xlabel('$x$')
ax.set_ylim(-a,a)
ax.set_xlim(-a,a)
ax.set_aspect('equal')
plt.show()
