# Chapter 37 MAGNETIC PROPERTIES OF MATTER¶

## Example 37.2 Orbital dipole moment¶

In [1]:
from __future__ import division
import math
e=1.6*10**-19 #in coul
r=5.1*10**-11 #radius of hydrogen atom in meter
m=9.1*10**-31 #mass of electron in kg
epsilon0=8.9*10**-12 #in coul2/nt-m2
p=((e**2)/4)*math.sqrt(r/(math.pi*epsilon0*m))
print("Orbital dipole moment in amp-m2 is %.3e"%p)

Orbital dipole moment in amp-m2 is 9.061e-24


## Example 37.4 Change in magnetic moment¶

In [2]:
from __future__ import division
e=1.6*10**-19 #in coul
r=5.1*10**-11 #radius of hydrogen atom in meter
m=9.1*10**-31  #mass of electron in kg
epsilon0=8.9*10**-12 #in coul2/nt-m2
B=2 #in wb/m2
delta_p=(e**2*B*r**2)/(4*m)
print("Change in Orbital dipole moment in amp-m2 is + 0r - %.3e"%delta_p)

Change in Orbital dipole moment in amp-m2 is + 0r - 3.659e-29


## Example 37.5 Precession frequency¶

In [3]:
from __future__ import division
import math
u=1.4*10**-26 #in amp-m2
B=0.50 #wb/m2
Lp=0.53*10**-34 #in joule-sec
fp=u*B/(2*math.pi*Lp)
print("Precession frequency of phoyon in given magnetic field in cps is %.2f"%fp)

Precession frequency of phoyon in given magnetic field in cps is 21020464.18


## Example 37.6 Magnetic ﬁeld strength Magnetisation Eﬀective magnetising current and Permeability¶

In [1]:
from __future__ import division
import math
n=10*10**2 #turns/m
i=2 #in amp
B=1.0 #in wb/m
u0=4*math.pi*10**-7 #in wb/amp-m
#(A)
H=n*i
print("(A) Magnetic field strength in amp/m is",H)
#(B)
M=(B-u0*H)/u0
print("(B)  Magnetisation is Zero when core is removed")
print(" Magnetisation when the core is replaced in amp/m %.2f"%M)
#(C)
print("(C) Effective magnetizing current i=i(M,0)=M*(2*math.pi*r0/N0)=M/n")
i=M/n
print(" Effective magnetizing current in amp is %.5f"%i)
#D
Km=B/(u0*H)
print("(D) Permeability %.5f"%Km)

('(A) Magnetic field strength in amp/m is', 2000)
(B)  Magnetisation is Zero when core is removed
Magnetisation when the core is replaced in amp/m 793774.72
(C) Effective magnetizing current i=i(M,0)=M*(2*math.pi*r0/N0)=M/n
Effective magnetizing current in amp is 793.77472
(D) Permeability 397.88736