# Chapter 20: Super Conducting Materials¶

## Example 20.2, page no-568¶

In :
# Critical field

import math
#variable declaration
h0=0.0306                   # critical field
t1=2.0                      # Temperature
t2=3.7                      # Temperature corresponds to h0

#calculation
he=h0*(1-((t1**2)/t2**2))

#Result
print("The critical field at %d K is %.5f T"%(t1,he))

The critical field at 2 K is 0.02166 T


## Example 20.3, page no-569¶

In :
# Critical current for a wire

import math
#variable declaration
t1=4.2                      # Temperature
t2=7.18                     # critical Temperature
h0=6.5*10**4                # critical magnetic field

#calculations
he=h0*(1-((t1**2)/t2**2))
r=0.5*10**-3
I=2*3.14*he*r

#Result
print("The critical current through a wire of lead is %.2f A"%I)

The critical current through a wire of lead is 134.26 A


## Example 20.4, page no-570¶

In :
#critical temperature

import math
#variable declaration
tc1=4.185                 # Critical temperature of lead
m1=199.5                  # isotopic mass 1
m2=203.4                  # isotopic mass 2

#calculation
tc2=tc1* math.sqrt(m1/m2)

#Result
print("The critical temperature for metal with isotopic mass of %.1f is %.3f K"%(m2,tc2))

The critical temperature for metal with isotopic mass of 203.4 is 4.145 K