ELECTRIC CURRENT
      Electric Current is the rate of flow of Electric charges through a conductor. 
The SI unit of Electric Current is Ampere (A).
One Ampere is equal to the flow of one Coulomb of electric charge per Second.

Def:  The amount of electric current in a metal is defined as the amount of electric 
charge flowing through the cross-sectional surface of the conductor over time. Mathematically,
    
         I = Q/T 
Where,

         I = Electric current in amperes,
        Q = Amount of charge in coulombs,
        T = Time in seconds.

The instantaneous current, i(t), at any particular time is obtained by differentiating the charge with respect to time:

                    
	
When a metal wire is connected to the two ends of a DC voltage source (such as a battery), it 
generates an electric current across the conductor. The free electrons of the conductor are forced 
to move to the positive terminal due to the electric field in the conductor. One coulomb of electric
 charge drifts (moves) per second through the conductor for one ampere of electric current. One coulomb 
of electric charge is equal to 6.242 x 1018 electrons.

	The flow of electrons can be modeled as a flow of free electrons that can scatter off the atoms of
 material in the conductor. This scattering prevents the electrons from constantly accelerating and gives
 them an average drift velocity.
	In this model, in order for some net charge to flow, the mobile charged particles within a conductor
 must move together with an average drift rate of:

                I = nAvQ  
Where,
  I is the electric current,
  n is number of charged particles per unit volume,
  A is the cross-sectional area of the conductor,
  v is the drift velocity, and
  Q is the charge on each particle.


Current Density is a measure of the density of the electric current. It is a vector quantity. Its magnitude 
is defined as the electric current per cross-sectional area. 

	The direction of the conventional current is opposite to the direction of the flow of electrons (negative charge),
 so it can be viewed as a flow of positive charges in the direction of the current, since that is equivalent to the opposing flow of electrons. 
 



Types of Electricity:

	1) Static electricity- no motion of free charges
	2) Current electricity- motion of free charges
	    ->Direct Current (DC)
	    ->Alternating Current (AC)

 


  Problems

      Accumulator ring antiproton beam current