# Superconducting Materials¶

## Example number 12.1, Page number 356¶

In :
#importing modules
import math

#Variable declaration
Tc=3.7;   #critical temperature in K
H0=0.0306;   #magnetic field in T
T=2;    #temperature in K

#Calculation
Hc=H0*(1-(T**2/Tc**2));
Hc=math.ceil(Hc*10**5)/10**5;   #rounding off to 5 decimals

#Result
print("critical field in T is",Hc);

('critical field in T is', 0.02166)


## Example number 12.2, Page number 356¶

In :
#importing modules
import math

#Variable declaration
Tc=7.26;   #critical temperature in K
H0=6.4*10**3;   #magnetic field in T
T=5;    #temperature in K

#Calculation
Hc=H0*(1-(T**2/Tc**2));
Hc=math.ceil(Hc*10**3)/10**3;   #rounding off to 3 decimals

#Result
print("critical field in T is",Hc);

('critical field in T is', 3364.385)


## Example number 12.3, Page number 357¶

In :
#importing modules
import math

#Variable declaration
Tc1=4.185;   #critical temperature in K
M1=199.5;     #atomic mass
M2=203.4;     #atomic mass after changing

#Calculation
#according to maxwell equation Tc*M^0.5=constant
#Tc1*M1^0.5=Tc2*M2^0.5
Tc2=(Tc1*M1**0.5)/M2**0.5;
Tc2=math.ceil(Tc2*10**6)/10**6;   #rounding off to 6 decimals

#Result
print("critical temperature of Hg in K is",Tc2);

('critical temperature of Hg in K is', 4.144685)


## Example number 12.4, Page number 357¶

In :
#importing modules
import math

#Variable declaration
d=1;    #diameter of wire in mm
T=4.2;       #temperature in K
Tc=7.18;   #critical temperature in K
H0=6.5*10**4;   #magnetic field

#Calculation
d=d*10**-3;     #diameter in m
R=d/2;
Hc=H0*(1-(T**2/Tc**2));
HC=Hc/10**4;
HC=math.ceil(HC*10**3)/10**3;   #rounding off to 2 decimals
Ic=2*math.pi*R*Hc;
Ic=math.ceil(Ic*10**2)/10**2;   #rounding off to 2 decimals
A=math.pi*R**2;
J=Ic/A;
J=J/10**8;
J=math.ceil(J*10**5)/10**5;   #rounding off to 5 decimals

#Result
print("critical magnetic field at 4.2K in A/m is",HC,"*10**4");
print("critical current in A is",Ic);
print("critical current density in A/m^2 is",J,"*10**8");

('critical magnetic field at 4.2K in A/m is', 4.276, '*10**4')
('critical current in A is', 134.33)
('critical current density in A/m^2 is', 1.71035, '*10**8')


## Example number 12.5, Page number 358¶

In :
#importing modules
import math

#Variable declaration
e=1.6*10**-19;
h=6.626*10**-34;
V=6;    #voltage applied in micro volts

#Calculation
V=V*10**-6;    #converting micro volts to volts
new=(2*e*V)/h;
new=new/10**9;
new=math.ceil(new*10**4)/10**4;   #rounding off to 4 decimals

#Result
print("frequency of ac signal in Hz is",new,"*10**9");

('frequency of ac signal in Hz is', 2.8977, '*10**9')


## Example number 12.6, Page number 358¶

In :
#importing modules
import math

#Variable declaration
Kb=1.38*10**-23;
Tc=7.19;    #critical temperature in K

#Calculation
Eg=3.5*Kb*Tc;
Eg=Eg/(1.6*10**-19);    #converting J to eV
Eg=Eg*10**3;    #converting eV into milli eV
Eg=math.ceil(Eg*10**3)/10**3;   #rounding off to 3 decimals

#Result
print("band gap of superconducting lead in meV is",Eg);

('band gap of superconducting lead in meV is', 2.171)

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