# Magnetic Materials¶

## Example number 8.1, Page number 238¶

In :
#To calculate the magnitude and direction of magnetic moment

#importing modules
import math

#Variable declaration
I = 12;          #current(Ampere)
A = 7.5*10**-4       #area of loop(m**2)

#Calculation
M = I*A;         #magnetic moment(Am**2)
M = M*10**3;

#Result
print "magnetic moment is",M,"*10**-3 Am**2"
print "M is directed away from the observer and is perpendicular to the plane of the loop"

magnetic moment is 9.0 *10**-3 Am**2
M is directed away from the observer and is perpendicular to the plane of the loop


## Example number 8.2, Page number 238¶

In :
#To calculate the magnetic moment

#importing modules
import math

#Variable declaration
r = 0.5;         #radius of orbit(Angstrom)
e = 1.6*10**-19;       #charge of electron(C)
new = 10**16;          #frequency(rps)

#Calculation
r = r*10**-10;         #radius of orbit(m)
I = e*new;             #current(Ampere)
A = math.pi*r**2;      #area enclosed(m**2)
M = I*A;               #magnetic moment(Am**2)

#Result
print "magnetic moment is",M,"Am**2"

magnetic moment is 1.25663706144e-23 Am**2


## Example number 8.3, Page number 239¶

In :
#To calculate the magnetic susceptibility

#importing modules
import math

#Variable declaration
mew_r = 5000;       #relative permeability

#Calculation
chi_m = mew_r-1;       #magnetic susceptibility

#Result
print "magnetic susceptibility is",chi_m

magnetic susceptibility is 4999


## Example number 8.4, Page number 239¶

In :
#To calculate the permeability

#importing modules
import math

#Variable declaration
H = 1800;       #magnetic field(A/m)
phi = 3*10**-5;         #magnetic flux(Wb)
A = 0.2;           #cross sectional area(cm**2)

#Calculation
A = A*10**-4;      #cross sectional area(m**2)
B = phi/A;         #magnetic flux density(Wb/m**2)
mew = B/H;         #permeability(H/m)
mew = mew*10**4;
mew=math.ceil(mew*100)/100;   #rounding off to 2 decimals

#Result
print "permeability is",mew,"*10**-4 H/m"

permeability is 8.34 *10**-4 H/m


## Example number 8.5, Page number 239¶

In :
#To calculate the magnetic moment

#importing modules
import math

#Variable declaration
B = 0.65;      #magnetic induction(Wb/m**2)
rho = 8906;       #density(kg/m**3)
M = 58.7;         #atomic weight
mew0 = 4*math.pi*10**-7;
mb = 9.27*10**-24;

#Calculation
N = rho*Na/M;         #number of atoms per unit volume(atoms/m**3)
mew_r = B/(N*mew0);         #relative permeability(A/m**2)
M = mew_r/mb;               #magnetic moment in mew_B
M=math.ceil(M*10**3)/10**3;   #rounding off to 3 decimals

#Result
print "magnetic moment is",M,"mew_B"

magnetic moment is 0.611 mew_B

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