# 12: Superconducting Materials¶

## Example number 12.1, Page number 328¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
M1=202;   #mass number of mercury
a=0.50;   #coefficient of mass number
T1=4.2;   #temperaturefor mass number 200(K)
M2=200;   #mass number of mercury

#Calculation
T2=((M1/M2)**a)*T1;   #The transition temperature for the isotope of mercury of mass number 200(K)

#Result
print "The transition temperature for the isotope of mercury of mass number 200 is",round(T2,4),"K"

The transition temperature for the isotope of mercury of mass number 200 is 4.2209 K


## Example number 12.2, Page number 328¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
Tc=9.15;   #critical temperature of Nb(K)
t=6;  #temperature of critical field(K)
Ho=0.196;  #The critical field AT 0K(T)

#Calculation
Hc=(Ho*(1-(t/Tc)**2));     #The critical field at 6K(T)

#Result
print "The critical field is",round(Hc,4),"T"

The critical field is 0.1117 T


## Example number 12.3, Page number 329¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
M1=199.5;   #Isotopic mass of metal
T1=4.185;   #Critical temperature for a metal with isotopic mass(K)
T2=4.133;   #fall of critical temperature for a metal with isotopic mass(K)
a=0.50;     #coefficient of mass

#Calculation
M2=(((M1)**a)*(T1/T2))**2;     #The Isotopic mass if the critical temperature falls to 4.133

#Result
print "The Isotopic mass if the critical temperature falls is",round(M2,2)

The Isotopic mass if the critical temperature falls is 204.55


## Example number 12.4, Page number 329¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
Hc=7.2*10**3;    #The critical magnetic field(A/m)
r=0.5*10**-3;    #radius of long thin superconducting wire(m)

#Calculation
Ic=(2*math.pi*Hc*r);     #The critical current through a long thin superconductor(A)

#Result
print "The critical current through a long thin superconductor is",round(Ic,3),"A"
print "answer varies due to rounding off errors"

The critical current through a long thin superconductor is 22.619 A
answer varies due to rounding off errors


## Example number 12.5, Page number 329¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
Tc=3.7;     #critical temperature of superconducting Sn(K)
t=2;   #temperature of critical field(K)
Ho=0.0306;   #The critical field at 0K(T)

#Calculation
Hc=(Ho*(1-(t/Tc)**2));    #The critical field at 6K(T)

#Result
print "The critical field is",round(Hc,6),"tesla"

The critical field is 0.021659 tesla


## Example number 12.6, Page number 329¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
Ho=6.5*10**4;   #The critical field at 0K(A/m)
Tc=7.18;    #The temperature for lead(K)
r=0.5*10**-3;   #radius of superconducting wire of lead(m)
T=4.2;    #temperature of superconducting wire(K)

#Calculation
Hc=(Ho*(1-(T/Tc)**2));    #The critical field(KA/m)
Ic=2*math.pi*Hc*r;    #The critical density for a superconducting wire of lead(A)

#Result
print "The critical density for a superconducting wire of lead is",round(Ic,2),"A"
print "answer varies due to rounding off errors"

The critical density for a superconducting wire of lead is 134.33 A
answer varies due to rounding off errors


## Example number 12.7, Page number 330¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
Hc=10**5;    #The critical field for vanadium(A/m)
Ho=2*10**5;   #The critical field for vanadium at 0K(A/m)
T=8.58;    #temperature for vanadium(K)

#Calculation
Tc=T/math.sqrt(1-(Hc/Ho));     #The critical temperature(K)

#Result
print "The critical temperature is",round(Tc,5),"K"

The critical temperature is 12.13395 K


## Example number 12.8, Page number 338¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
V=5.9*10**-6;     #voltage applied across a Josephson junction(V)
e=1.6*10**-19;     #charge of electron(c)
h=6.62*10**-34;    #Planck's constant(J-sec)

#Calculation
v=(2*e*V)/h;     #The frequency of the radiation emitted by the junction(Hz)

#Result
print "The frequency of the radiation emitted by the junction is",round(v/10**9,5),"*10**9 Hz"

The frequency of the radiation emitted by the junction is 2.85196 *10**9 Hz