test.py

import numpy as np
import matplotlib.pyplot as plt

dt = 0.01
Br = 13500.0
R = 15 * (10 ** -3)
D = 10**-6


def Z(t):
    A = 1.0
    w = 4.0
    return(A*np.cos(w*t))

def Phi(t:float):
    Br = 13500.0
    R = 15 * (10 ** -3)
    D = 10**-6
    return(Br/2*np.pi*R*((D + Z(t))/np.sqrt(R**2 + (D+R)**2) + Z(t)/np.sqrt(R**2+Z(t)**2)))


Temps = [k*dt for k in range(1000)]
PhiT = []
for t in Temps[1:len(Temps)-1]:
    PhiT.append( (Phi(t+dt) - 2 * Phi(t) + Phi(t-dt)) /dt**2 )

plt.plot(Temps[1:len(Temps)-1], PhiT)
plt.title("chage condo")
plt.show()