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Current Electricity

Electric Current (I)
  • It is the rate of flow of electric charge flowing though any section of wire.
Ohm’s Law
  • Electric current flowing through a conductor is directly proportional to the potential difference across the two ends of the conductor; physical quantities such as temperature, mechanical strain, etc. remaining constant.
   V = RI
Where, R is a constant for a given conductor
Electrical resistance:
        R=ρlA
         Where, r is the specific resistance or electrical resistivity of the material
 
Conductance and Electrical conductivity:
  •   Conductance G=Aρl
  • Electrical conductivity (s) is defined as the reciprocal of resistivity.
   σ=1ρ
The other form of Ohm's law is 
J= σE
J = current density
E = electric field applied
 Motion of electrons due to thermal energy
 
  • Free electrons are in continuous random motion. They undergo change in direction at each collision and the thermal velocities are randomly distributed in all directions.
  • Average thermal velocity,u=u1+u2+u3+........+unn is zero … (1)
  •  
Drift velocity
  • vd is defined as the velocit…

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