Download Engineering Electromagnetic

Engineering Electromegnetic
Engineering Electromagnetic
SUB : Engineering Electromagnetic
Topic : Conductors
Department : Electronics and communication
Name : Parmar Taruna M.
Enroll No : 130430111110
Guided By, j .m bhoot
A conductor is something which allows electricity to flow through.
Exam.: Scissors, Paper clip, Aluminum foil,Iron,Steel,Copper.
In Conductors Valence electronics are present.
When an electric field is applied ,then these electrons start moving which
constitute an electric current.
Conductors are the materials which allow the current to flow very easily.
Fig. Energy band diagram for conductors
This is due to the large number of free electrons
present in conductors.
Look at the energy band diagram of conductor show
fig. for metals like copper , alumina, etc.
There is no “forbidden gap” present between the
valence and conductors bands.
Therefor even at room temperature , a large number
of free electrons are present and available for
conduction.
When a charge Q is placed in an electric field E, it experiences a force
Gives by F=QE. If this charge is an electrons, then Q=-e so that F=-e E . Due to
negative sign of elections charge it is clear that the force acting on the electron is in
opposite direction to that of eclectic field intensity E. If there is no opposition or
resistance to the motion of electron, then the velocity of electron will increase
indefinitely with the time t provided the electron field E is constant.
Lets us now consider a conductor placed in a static electric field , as
show fig. the free electrons in the conductor moves opposite to the
direction line of electric field .
Thus a negative surface charge forms on the boundary accompanied
by an equal amount of positive surface charge show in fig. ,since the
conductor as a whole is neutral.
Fig : Effect of Field Conductor
* Imagine that you have a solid metal ball or sphere and you place charge
inside of it.
* How fast this charge arrives at the surface can be calculated using the term
relaxation time .
* Time taken by charges to travel to the surface is represented by relaxation
time. Using the relations,
In electrostatic fields, following principle are applicable to conductors:
Within a Conductor, charge or change density(pv c/ m3) is zero and a
surface charge density (ps c/m3) is present on the other surface of the
conductor.
The tangential component of external electrical field intensity as well as
electric flux density is zero.
The conductor surface is an equipotential surface.
The normal component of electric flux density is equal to surface charge
density on the conductor surface.
*
References
1.www.wikipedia.in
2.www.google.com
3.www.yahoo.com