# 11: Electrostatics and electromagnetic theory¶

## Example number 11.1, Page number 279¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
mew = 1;      #parameter of aluminium
sigma = 3.54*10**7;      #conductivity(mho/m)
delta = 0.01*10**-3;       #skin depth of aluminium(mm)

#Calculation
new = 1/((delta**2)*math.pi*mew*sigma);       #frequency(Hz)
new = math.ceil(new*10**2)/10**2;   #rounding off to 2 decimals

#Result
print "frequency is",new,"Hz"
print "answer given in the book is wrong"

frequency is 89.92 Hz
answer given in the book is wrong


## Example number 11.2, Page number 280¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
se = 2;         #solar energy(cal /min /cm**2)
j = (4.2*10**4)/60;       #conversion factor from cal /min /cm**2 to J /m**2 /sec)
mew0 = 4*math.pi*10**-7;         #permeability of free space(H/m)
epsilon0 = 8.854*10**-12;        #permittivity of free space(F/m)

#Calculation
EH = se*j;         #solar energy(J /m**2 /sec)
EbyH = math.sqrt(mew0/epsilon0);
EbyH = math.ceil(EbyH*10)/10;   #rounding off to 1 decimal
H = math.sqrt(EH/EbyH);         #magnetic field of radiation
E = EbyH*H;
H = math.ceil(H*10**3)/10**3;   #rounding off to 3 decimals
E = math.ceil(E*10)/10;   #rounding off to 1 decimal
E0 = E*math.sqrt(2);        #electric field of radiation(volt/m)
H0 = H*math.sqrt(2);        #magnetic field of radiation (amp-turn/m)
H0 = math.ceil(H0*10**2)/10**2;   #rounding off to 2 decimals

#Result
print "electric field of radiation is",int(E0),"volt/m"
print "magnetic field of radiation is",H0,"amp-turn/m"

electric field of radiation is 1027 volt/m
magnetic field of radiation is 2.73 amp-turn/m


## Example number 11.3, Page number 280¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
p = 4.3*10**-8;         #polarization(C/m**2)
E = 1000;              #electric field(V/m)
epsilon0 = 8.85*10**-12;        #permittivity of free space(F/m)

#Calculation
epsilonr = 1+(p/(epsilon0*E));         #relative permittivity
epsilonr = math.ceil(epsilonr*10**2)/10**2;   #rounding off to 2 decimals

#Result
print "relative permittivity is",epsilonr

relative permittivity is 5.86