python help please how can I add 3 more graphs in one graph :

t1= np.linspace(0,3600,11)

t2=np.linspace (0,3600,101)

t3=np.linspace(0,3600,1001)

to my code:

import numpy as np

import matplotlib.pyplot as plt

N=3

D=10**(-15)

l=10**(-5)

t_start=0

t_end=3600

n_steps=11

y=[]

time=np.linspace(t_start,t_end,n_steps)

for t in time:

su=0

for p in range(1,N+1):

v1= ((2*p)-1)**2

power=-(v1*(np.pi**2)*D*t)/(l**2)

val = (1/v1)*(np.e**power)

su = su + val

m_film=1-((8/(np.pi**2))*su)

y.append(m_film)

x=time

fig1 = plt.gcf()

plt.plot(x,y)