import math
# Variable declaration
r = 0.53*10**-10; # orbit radius m
n = 6.6*10**15; # frequency of revolution of electronHz
e = 1.6*10**-19 # charge of electron in coulombs
h = 6.63*10**-34; # plancks constant in J.s
m = 9.1*10**-31; # mass of electron in kg
# Calculations
i = e*n # current produced due to electron
A = math.pi*r*r # Area in m^2
u = i*A; # magnetic moment A*m^2
ub = (e*h)/float(4*math.pi*m); # Bohr magneton in J/T
#result
print'Magnetic moment = %3.3e'%u,'Am**2';
print'Bohr magneton = %3.2e'%ub,'J/T';
import math
#Variable declaration
ur = 1150; # relative permeability
n = 500; # turns per m
V = 10**-3; # volume of iron rod in m**3
i = 0.5; # current in amp
#Calculations
#B = uo(H+M)
# B = uH, u/uo = ur
# M = (ur - 1)H
#if current is flowing through a solenoid having n turns/l then H = ni
M = (ur - 1)*n*i # magnetisation
m = M*V; # magnetic moment
#Output
print'Magnetic moment = %3.2e'%m,' A-m**2';
print'\n Note: Instead of 2.87*10**2, 2.87*10**-2 is printed in textbook';
import math
# Variable declaration
ur = 90; #relative permeability
n = 300; # turns per m
i = 0.5; # current in amp
d = 10*10**-3; # diameter of iron rod
l = 2; # length of iron rod
#Calculations
V = math.pi*(d/float(2))**2 * l; #volume of rod
M = (ur - 1)*n*i; # magnetisation
m = M*V; # magnetic moment
# Output
print'Magnetic Moment of the rod = %3.3g'%m,'A-m**2';
print'Note: In textbook length of iron rod given as 2m whereas in calculation it is wrongly taken as 0.2m';
import math
#Variable declaration
Bo = 2; # magnetic field in tesla
r = 5.29*10**-11 # radius in m
m = 9.1*10**-31; # mass of electron in kg
e = 1.6*10**-19 # charge of electron
# calculations
du = (e**2 * Bo * r**2)/float(4*m); # change in magnetic moment(indicating oth in -ve and +ve values)
#result
print'Change in magnetic moment = %3.1e'%du,'J/T';
import math
# Variable declaration
u1 = 3.3; # magnetic dipole moment
u = 9.24*10**-24;
B = 5.2; # magnetic field in tesla
k = 1.38*10**-23; # boltzmann constant
# calculations
T = (u*u1*B)/float(1.5*k); # Temperature in Kelvin
#result
print'Temperature to which substance to be cooled = %3.1f'%T,'K';
print'Note:Values given in question B = 52, u = 924*10**-24.Values substituted in calculation B = 5.2, u = 9.24*10**-24';
import math
#Variable declaration
xm = -4.2*10**-6; # magnetic susceptibility in A.m**-1
H = 1.15*10**5; # magnetic field in A.m**-1
#Calculations
uo = 4*math.pi*10**-7; # magnetic permeability N·A**-2
M = xm*H; # magnetisation in A.m**-1
B = uo*(H + M); # flux density in T
ur = 1+(M/float(H)); # relative permeability
# result
print'Magnetisation = %3.2f'%M,'A/m';
print'flux density = %3.2f'%B,'Tesla';
print'relative permeability = %f'%ur;
import math
# Variable declaration
xm = 1.4*10**-5; # magnetic susceptibility
# B = uoH
# B' = uruoH
# ur = 1+xm
# from above equations
#B' = (1+xm)B
# percentage increase in magnetic induction = ((B'-B)/B)*100
# y = (((1+xm)B - B)/B)*100
PI = xm*100; # percentage increase
# Output
print'Percentage increase = %3.4f'%PI,'%';
import math
# Variable declaration
xm = -0.2*10**-5; # magnetic susceptability in A.m**-1
H = 10**4; # magnetic field in A/m
# Calculations
uo = 4*math.pi*10**-7; # magnetic permeability
M = xm*H # magnetisation in A/m
B = uo*(H+M); # magnetic flux density in T
# Output
print'magnetisation = %3.2f'%M,'A/m';
print'Note:magnetisation sign is printed wrong in textbook';
print'Magnetic flux density = %3.4f'%B,'T';
import math
#variable declaration
sighem = 2.1*10**-5; #magnetic susceptability
u1 = 10**-7;
#calculation
u0 = 4*math.pi*u1;
ur = 1+(sighem); #permeability
u = u0*ur; #relative permeability in N/A**2
#result
print'permeability =%3.6f'%ur;
print'relative permeability =%3.4e'%u,'N/A**2';
import math
#variable declaration
sighem = 0.084; #magnetic susceptability
u1 = 10**-7;
#calculation
u0 = 4*math.pi*u1;
ur = 1+(sighem); #permeability
u = u0*ur; #relative permeability in N/A**2
#result
print'permeability =%3.6f'%ur;
print'relative permeability =%3.3e'%u,'N/A**2';
import math
#variable declarationn
u = 0.126; #permiability in N/A**2
u1 = 10**-7;
#calculation
u0 = 4*math.pi*u1;
ur = u/float(u0);
sighe = ur-1; #magnetic susceptability
#result
print'relative permiability =%3.5e'%sighe;
print' Note:Calculation mistake in textbook in calculating sighe by taking ur as 10**5 instead of 100318.4';
import math
#variable declaration
#diamagnetic susceptability of He
R = 0.6*10**-10; #mean radius of atom in m
N = 28*10**26; #avagadro number in per m**3
e = 1.6*10**-19; #charge of electron in coulombs
m = 9.1*10**-31; #mass of electron in kilograms
Z = 2; #atomic number
#calculation
u0 = 4*math.pi*10**-7; #atomic number
si = -(u0*Z*(e**2)*N*(R**2))/float(6*m); #susceptability of diamagnetic material
#result
print'susceptability of diamagnetic material = %3.4e'%si;
import math
#variable declaration
phi = 2*10**-5; #magnetic flux in Wb/m**2
H = 2*10**3; #in A/m
A = 0.2*10**-4; #area in m**2
#calculation
u0 = 4*math.pi*10**-7;
B = phi/float(A); #magnetic flux density in Wb/m**2
u = B/float(H); #permiability in A**-2
sighem = (u/float(u0))-1;
#result
print'permiability =%3.2e'%u,'N/A**2';
print'susceptability =%4f'%sighem;
print'Note:answer of permiability is wrong in textbook';
print'Note: calcuation mistake in textbook in sighem';
# import math
#variable declaration
N = 6.5*10**25; #number of atoms in atoms per m**3
e = 1.6*10**-19; #charge of electron in coulombs
m = 9.1*10**-31; #mass of electron inilograms
h = 6.6*10**-34; #planck's constant in J.s
T = 300; #temperature in K
k = 1.38*10**-23; #boltzman constant in J*(K**-1)
n = 1; #constant
#calculation
u0 = 4*math.pi*10**-7;
M = n*((e*h)/float(4*math.pi*m)); #magnetic moment in A*m**2
sighe = (u0*N*(M**2))/float(3*k*T); #susceptability of diamagnetic material
#result
print'susceptability of diamagnetic material = %3.2e'%sighe;
import math
#variable declaration
L = 2.0; #length in m
A = 4*10**-4; #cross section sq.m
u = 50*10**-4; #permiability in H*m**-1
phi = 4*10**-4; #magnetic flux in Wb
#calculation
B = phi/float(A); #magnetic flux density in Wb/m**2
NI = B/float(u); #ampere turn in A/m
#result
print'ampere turn =%3.0f'%NI,'A/m';
import math
#variable declaration
H = 5*10**3; #corecivity in A/m
l = 10**-1; #length in m
n = 500; #number of turns
#calculation
N = n/float(l); #number of turns per m
i = H/float(N); #current in A
#result
print'current =%1d'%i,'A';
import math
#variable declaration
A = 6*10**-4; #area in m**2
l = 0.5; #length in m
u = 65*10**-4; #permiability in H/m
phi = 4*10**-5; #magnetic flux in Wb
#calculation
B = phi/float(A);
H = B/float(u);
N = H*l; #number of turns
#result
print'number of turns =%1f'%N;
print' Note: calculation mistake in textbook in calculattig H by taking B value as 0.06 instead of 0.0666';
import math
#variable declaration
A = 0.2*10**-4; #area in m**2
H = 500; #magnetising field in A.m**-1
phi = 2.4*10**-5; # magnetic flux in Wb
#calculation
u0 = 4*math.pi*10**-7;
B = phi/float(A); #magnetic flux density in N*A**-1 *m**-1
u = B/float(H); #permiability in N/m
fm = (u/float(u0))-1; #susceptability
#result
print'susceptability =%3.2d'%fm;
import math
#variable declaration
f = 50; #number of reversals/s in Hz
W = 50; #weight in kg
d = 7500; #density in kg/m^3
A = 200; #area in joules /m^3
#calculation
V = 1/float(d); #volume of 1 kg iron
E = A*V; #loss of energy per kg
L = f*E; #hysteresisloss/s in Joule/second
Lh = L*60*60; #loss per hour
#calculation
print'loss of energy per hour =%3.2f'%Lh;
print'Note:calculation mistake in textbook in calculating Lh';
import math
#variable declaration
f = 50; #frequency in Hz
Bm = 1.1; #magnetic flux in Wb/m**2
t = 0.0005; #thickness of sheet
p = 30*10**-8*7800; #resistivity in ohms m
d = 7800; #density in kg/m**3
Hl = 380; #hysteresis loss per cycle in W-S/m**2
#calculation
Pl = ((math.pi**2)*(f**2)*(Bm**2)*(t**2))/float(6*p); #eddy current loss
Hel = (Hl*f)/float(d); #hysteresis loss
Tl = Pl+Hel; #total iron loss watt/kg
#result
print'total iron loss =%3.2f'%Tl,'watt/kg';