title: TypeError: only length-1 arrays can be converted to Python scalars with NUMPY
body: <pre><code># -*- coding: utf-8 -*-
  import matplotlib.pyplot as plt 
  import numpy as np 
  import math
  
  
  #task 2e
  
  x = np.linspace(-0.0001,0.1,50) 
  
  #constants
  e0=8.85*10 ** (-12)
  
  r0=3 * 10 ** (-3)
  Q=2 * 10** (-9)
  
  Q2=10 * 10*(-9)
  r2=5*10**(-3)
  
  
  v=(Q/((4*math.pi*e0)*(math.sqrt((x**2+r0**2)))))
  
  
  v2=v+(Q2/((4*math.pi*e0)*(math.sqrt(((x-2)**2+r2**2)))))
  
  plt.plot(x, v)
  plt.plot(x, v2)
  plt.xlabel("Meter")
  plt.ylabel("V1/2(x)")
  </code></pre>
  
  <p>Running this code gives the following TypeError:</p>
  
  <blockquote>
    <p>TypeError: only length-1 arrays can be converted to Python scalars 
    On 21 v=(Q/((4*math.pi*e0)<em>(math.sqrt((x</em>*2+r0**2)))))</p>
  </blockquote>