# 15: Superconductivity¶

## Example number 1, Page number 442¶

In [4]:
#importing modules
import math
from __future__ import division

#Variable declaration
H0=0.0106;          #critical field at 0K(Tesla)
T=3;                #temperature(K)
Tc=4.7;             #temperature(K)

#Calculation
Hc=H0*(1-(T/Tc)**2);     #critical field at 3K(Tesla)

#Result
print "critical field at 3K is",round(Hc,6),"Tesla"
print "answer given in the book is wrong"

critical field at 3K is 0.006281 Tesla
answer given in the book is wrong


## Example number 2, Page number 442¶

In [6]:
#importing modules
import math
from __future__ import division

#Variable declaration
H0=5*10**5/(4*math.pi);          #critical field at 0K(Tesla)
Tc=2.69;                         #temperature(K)
Hc=3*10**5/(4*math.pi);          #critical field(Tesla)

#Calculation
T=Tc*math.sqrt(1-(Hc/H0));       #temperature(K)

#Result
print "temperature of superconductor is",round(T,3),"K"

temperature of superconductor is 1.701 K


## Example number 3, Page number 443¶

In [9]:
#importing modules
import math
from __future__ import division

#Variable declaration
H0=6.5*10**4;          #critical field at 0K(Tesla)
Tc=7.28;               #temperature(K)
T=4.2;                 #temperature(K)

#Calculation
Hc=H0*(1-(T/Tc)**2);          #critical field(Tesla)
Ic=2*math.pi*r*Hc;            #critical current of the wire(A)

#Result
print "critical field is",round(Hc/10**4,4),"*10**4 A/m"
print "critical current of the wire is",int(Ic),"A"

critical field is 4.3365 *10**4 A/m
critical current of the wire is 408 A


## Example number 4, Page number 443¶

In [11]:
#importing modules
import math
from __future__ import division

#Variable declaration
m1=199.5;             #isotopic mass
m2=205.4;             #change in mass
Tc1=4.185;            #temperature of mercury(K)

#Calculation
Tc2=Tc1*math.sqrt(m1/m2);     #critical temperature(K)

#Result
print "critical temperature is",round(Tc2,3),"K"

critical temperature is 4.124 K


## Example number 5, Page number 444¶

In [13]:
#importing modules
import math
from __future__ import division

#Variable declaration
T1=3;            #temperature(K)
T2=8;            #temperature(K)
lamda1=39.6;     #penetration depth(nm)
lamda2=173;      #penetration depth(nm)

#Calculation
x=(lamda1/lamda2)**2;
Tc4=(T2**4-(x*T1**4))/(1-x);
Tc=Tc4**(1/4);   #superconducting transition temperature(K)

#Result
print "superconducting transition temperature is",round(Tc,3),"K"

superconducting transition temperature is 8.106 K