Chapter 15 Classification of Magnetic Materials

Example 15.1 Page no 457

In [17]:
#Given
q=0.12                      #TA**-1m
q1=4*math.pi*10**-7         #TA**-1m

#Calculation
import math
q3=q/q1
e=q3-1

#Result
print"Relative permeability is",round(q3*10**-4,2),"10**4"
print"susceptibility is",round(e*10**-4,2),"10**4"

Relative permeability is 9.55 10**4
susceptibility is 9.55 10**4

Example 15.2 Page no 457

In [66]:
#Given
A=0.5*10**-4                 #m**2
H=1200                       #Am**-1
W=599
Q=4*math.pi*10**-7          #TA"**-1m

#Calculation
import math
Z=Q*(1+W)
Z1=Z*H
Z2=Z1*A

#Result
print"(i) Z produced is",round(Z*10**4,2),"10**-4","TA**-1m"
print"(ii) Z1 produced is",round(Z1,3),"T"
print"(iii) Z2 produced is",round(Z2*10**5,3),"10**-5"

(i) Z produced is 7.54 10**-4 TA**-1m
(ii) Z1 produced is 0.905 T
(iii) Z2 produced is 4.524 10**-5

Example 15.3 Page no 457

In [73]:
#Given
I=1.2                           #A
Q=800
A=0.15                          #m
S=3500
K=4*math.pi*10**-7

#Calculation
import math
L=2*math.pi*A
n=S/L
B=(K*Q*S*I)/L

#Result
print"The magnetic field in the core for a magnetising current of 1.2 A is",B,"T"

The magnetic field in the core for a magnetising current of 1.2 A is 4.48 T

Example 15.4 Page no 457

In [90]:
#Given
H=2*10**3                       #Am**-1
I=4.8*10**-2                    #Am**-1
T=280                           #K
T1=320.0                          #K

#Calculation
S=I/H
S1=S*(T/T1)
S2=S1*H

#Result
print"The susceptibility of aluminium is raised to 280 k is",S*10**5,"10**3"
print"The temperature of the aluminium is raised to 320 k is",S1
print"The suscepitibility and intensity of magnetistionis",S2*10**2,"10**-2","Am**-1"

The susceptibility of aluminium is raised to 280 k is 2.4 10**3
The temperature of the aluminium is raised to 320 k is 2.1e-05
The suscepitibility and intensity of magnetistionis 4.2 10**-2 Am**-1

Example 15.5 Page no 458

In [95]:
#Given
W=3.2*10**4                    #J
M=8.4
D=7200
v=50                           #cycle s**-1
T=30*60                        #s

#Calculation
V=M/D
Q=W/(V*v*T)

#Result
print"The value of energy is",round(Q,1),"J m**-3 cycle**-1"

The value of energy is 304.8 J m**-3 cycle**-1

Example 15.6 Page no 458

In [16]:
#Given
m=4.5                            #Am
l=0.06                           #m
A=0.9*10**-4                     #m**2
r=0.06                           #m
J=4*math.pi*10**-7

#Calculation
I=m/A
H1=m/(4*math.pi*r**2)
H2=m/(4*math.pi*r**2)
H=H1+H2
B=J*(-H+I)

#Result
print"(a) Intensity of the magnetisation is", I*10**-4,"10**4 A/m"
print"(b) Magnetic intensity is",round(H,0),"A/m"
print"(c) Magnetic induction is",round(B*10**2,2),"*10**-2 T"

(a) Intensity of the magnetisation is 5.0 10**4 A/m
(b) Magnetic intensity is 199.0 A/m
(c) Magnetic induction is 6.26 *10**-2 T

Example 15.7 Page no 458

In [18]:
#Given
m=1.5*10**-23                            #J/T
n=2.0*10**24
a=15                                     #%
T1=4.2                                    #K
T2=2.8
B1=0.84                                    #T
B2=0.98

#Calculation
M=m*n
M1=M*(a/100.0)
M2=M1*T1*B2/(T2*B1)

#Result
print"Total dipole moment is",M2,"J/T"

Total dipole moment is 7.875 J/T