Electric field lines and flux

Electric field lines :- These are the imaginary lines which shows the electric field in a conductor.
It has following properties :-

1. These are imaginary open curves.
2. They travel from positive (+) to negative (-).
3. These are never intersect each other.
4. A tangent line on these line at a point shows the direction of electric field at that point.
5. Where quantity of electric field lines is high there intensity of electric field also high. Like in a dipole electric field intensity is high at both poles of dipole.
   

Electric flux :- It is the total numbers of electric field lines passing through any close surface.
It is the scalar product of electric field (E) and surface area of close surface(A).
It is denoted by ɸ.
ɸ = EA Cosθ

It surface area is small then electric flux is given by
dɸ = EdA Cosθ
ɸ = ∫dɸ = ∫ EdA Cosθ
here θ is angle formed between electric field and surface area.