The space surrounding an electric charge in which other charge experience a force of attraction or repulsion is called electric field.
Intensity of Electric Field : Electric field intensity at any point is defined as the electrostatic force acting per unit positive charge at that point. It is a vector quantity and its direction is same as the direction of F.
E = F/q NC-1
Electric Field Lines : An electric line of force is that imaginary smooth curve drawn in an electric field along which a free isolated unit positive charge moves.
The tangent drawn at any point on the electric line of force gives the direction of the force acting on a positive charge placed at that point.
Electric field lines come out of a positive charge and go into the negative charge. No two electric field lines can intersect each other.
Electric Dipole : An electric dipole consists of two equal and opposite charges (q) separated by a small distance (2d)
Electric dipole moment (p) = q x 2d
Its SI unit is C-m and dimension formula is [L1T1A1]
Electric Flux : Electric flux is the measure of number of electric field lines passing through any surface.
△ϕ = E.△S = E△S cosθ
where, △S area of surface.
Its SI unit is N-m2C-1.
Gauss' Theorem : The electric flux over any closed surface is 1/ε0 times the total charge enclosed by the surface.
ϕ = q/ε0
