# Electric Field

Electric field-The region around a particular charge in which its electrical effects can be observed is called the electric field of the charge

-Electric field has its own existence and is present even if there is no charge to experience the electric force.

Electric field Intensity:

E=F/q0

Where F is the electric force experience by the test charge q0 at this point.
It is the vector quantity

Some point to note on this1.Electric field lines extend away from the positive charge and towards thge negative charges
2. Electric field produces the force so if a charge q is placed in the electric field E the force experience by the charge is
F=qE
3 Principle of superposition also applies to electric field
so E=E1+E2+E3+E4+......

Electric field intensity due to point charge
E=KQr/r2
Where r is the distance from the point charge and r is the unit vector along the direction from source to point.

Some useful Formule
Electric field for the Uniformly charged ring

E=KQx/(r2+x2)3/2
Where x is the distance from the center of the ring
At x=0
E=0
Electric Field due to uniformly charged disc
E=(σ/2ε0)(1- x/(√R2+x2))
σ=Surface charge density of the disc
At x=0
E=σ/2ε0

Electric Field Intensity due to Infinite sheet of the charge
E=σ/2ε0
σ=Surface charge density of the sheet