import numpy as np

# Constants

epsilon$\_0=8\mathrm{.}85$e$-12$ # C$^2/($N$$m$^2)$

q $=$ Q $=2$e$-5$ # C

a $=0\mathrm{.}9$ # m

# Define the force function

def force$($x$)$:

return $(1/(4*$ np$.$pi $*$ epsilon$\_0))*($q $*$ Q $*$ x$)/(($x$**2+$ a$**2)**(3/2))$

# Calculate the distance where the force is maximum

x$\_$max $=$ np$.$sqrt$(0\mathrm{.}405)$

# Calculate maximum force at this distance

max$\_$force $=$ force$($x$\_$max$)$

x$\_$max, max$\_$force