Magnetic materials

Example number 10.1, Page number 305

In [1]:
#importing modules
import math

#Variable declaration
H=10**6;    #magnetic field strength in A/m
chi=0.5*10**-5;    #magnetic susceptibility

#Calculation
mew0=4*math.pi*10**-7;
M=chi*H;
B=mew0*(M+H);
B=math.ceil(B*10**3)/10**3;   #rounding off to 3 decimals

#Result
print("intensity of magnetisation in A/m is",M);
print("flux density in Wb/m^2 is",B);

('intensity of magnetisation in A/m is', 5.0)
('flux density in Wb/m^2 is', 1.257)

Example number 10.2, Page number 306

In [5]:
#importing modules
import math

#Variable declaration
A=6.022*10**23;     #avagadro number
mew0=4*math.pi*10**-7;
w=58.7;       #atomic weight of Ni
B=0.65;    #saturation magnetic induction in Wb/m^2
rho=8906;    #density in kg/m^3

#Calculation
rho=rho*10**3;     #converting into gm/m^3
N=(rho*A)/w;
mew_m=B/(N*mew0);
#mew_m/(9.27*10^-24) gives mew_m in mewB
mew_m=mew_m/(9.27*10**-24);
mew_m=math.ceil(mew_m*10**3)/10**3;   #rounding off to 3 decimals

#Result
print("magnetic moment of Ni is",mew_m,"mew_b");
#that is mew_m=0.61 mew_b

('magnetic moment of Ni is', 0.611, 'mew_b')

Example number 10.3, Page number 306

In [6]:
#importing modules
import math

#Variable declaration
mew_0=4*math.pi*10**-7;
H=1800;       #magnetic field in A/m
phi=3*10**-5;     #magnetic flux in Wb
A=0.2;     #area of cross section in cm^2

#Calculation
A=A*10**-4;   #area in m^2
B=phi/A;
mew_r=B/(mew_0*H);
mew_r=math.ceil(mew_r*10**3)/10**3;   #rounding off to 3 decimals

#Result
print("permeability of material is",mew_r);

('permeability of material is', 663.146)

Example number 10.4, Page number 307

In [8]:
#importing modules
import math

#Variable declaration
mew=18.4;       #magnetic moment in mew_b
a=0.835;     #lattice parameter in nm

#Calculation
mew=mew*9.27*10**-24;
a=a*10**-9;    #converting nm to m
V=a**3;
M=mew/V;
M=M/10**5;
M=math.ceil(M*10**4)/10**4;   #rounding off to 4 decimals

#Result
print("saturation magnetisation in A/m is",M,"*10**5");

('saturation magnetisation in A/m is', 2.9299, '*10**5')

Example number 10.5, Page number 307

In [9]:
#importing modules
import math

#Variable declaration
mew_0=4*math.pi*10**-7;
H=2*10**5;     #magnetic field strength in A/m
mew_r=1.01;    #relative permeability

#Calculation
B=mew_0*mew_r*H;
B=math.ceil(B*10**5)/10**5;   #rounding off to 3 decimals
M=(B/mew_0)-H;
M=math.ceil(M*10**2)/10**2;   #rounding off to 2 decimals

#Result
print("magnetic flux density in Wb/m^2 is",B);
print("magnetisation in A/m is",M);

#answer for magnetisation given in the book is wrong

('magnetic flux density in Wb/m^2 is', 0.25385)
('magnetisation in A/m is', 2007.42)

Example number 10.6, Page number 307

In [14]:
#importing modules
import math

#Variable declaration
mew_0=4*math.pi*10**-7;
H=500;      #magnetic field strength in A/m
chi=1.2;    #susceptibility

#Calculation
M=chi*H;
B=mew_0*(M+H);
B=B*10**3;
B=math.ceil(B*10**4)/10**4;   #rounding off to 4 decimals

#Result
print("magnetic flux density in Wb/m^2 is",B,"*10**-3");

('magnetic flux density in Wb/m^2 is', 1.3824, '*10**-3')
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