ELECTROMAGNETIC THEORY(EC1253)
1.State stokes theorem.
The line integral of a vector around a closed path is equal to the surface integral of the
normal component of its curl over any surface bounded by the path
H.dl = (ÑxH)ds
2.State coulombs law.
Coulombs law states that the force between any two point charges is directly
proportional to the product of their magnitudes and inversely proportional to the square
of the distance between them. It is directed along the line joining the two charges.
F=Q1Q2 / 4πεr
2 ar
3.State Gauss law for electric fields
The total electric flux passing through any closed surface is equal to the total charge
enclosed by that surface.
4.Define electric flux.
The lines of electric force is electric flux.
5.Define electric flux density.
Electric flux density is defined as electric flux per unit area.
6.Define electric field intensity.
Electric field intensity is defined as the electric force per unit positive charge.
E =F/ Q
=Q/4πεr2 V/m
7.Name few applications of Gauss law in electrostatics.
Gauss law is applied to find the electric field intensity from a closed surface.e.g)Electric
field can be determined for shell, two concentric shell or cylinders etc.
8.What is a point charge?
Point charge is one whose maximum dimension is very small in comparison with any
other length.
9.Define linear charge density.
It is the charge per unit length.
10.Write poisson’s and laplace ’s equations.
Poisson ‘s eqn:
Ñ2V= - ρv / ε
Laplace’ s eqn:
Ñ2V= 0
11.State the condition for the vector F to be solenoidal.
Ñ·F =0
12. .State the condition for the vector F to be irrotational.
ÑxF =0
13.Define potential difference.
Potential difference is defined as the work done in moving a unit positive charge
from one point to another poi