#importing modules
import math
from __future__ import division
#Variable declaration
Bc0=0.0305; #critical field(T)
T=2; #temperature(K)
Tc=3.722; #critical temperature(K)
r=2*10**-3; #diameter(m)
mew0=4*math.pi*10**-7; #magnetic permeability
#Calculation
BcT=Bc0*(1-(T/Tc)**2); #critical field(T)
Ic=2*math.pi*r*BcT/mew0; #current(A)
#Result
print "current is",round(Ic,1),"A"
#importing modules
import math
from __future__ import division
#Variable declaration
lamda0=37; #london penetration depth(nm)
T=5.2; #temperature(K)
Tc=7.193; #critical temperature(K)
#Calculation
a=1-(T/Tc)**4;
lamdaT=lamda0*(a**(-1/2)); #penetration depth of lead(nm)
#Result
print "penetration depth of lead is",round(lamdaT,3),"nm"