Question

what is flux of electric field

Answer 1

When a coil of wire is moved through a magnetic field a voltage is generated which depends on the magnetic flux through the area of the coil. In the case of an electric generator where the magnetic field penetrates a rotating coil, the area used in defining the flux is the projection of the coil area onto the plane perpendicular to the magnetic field. 

Answer 2

The total measurement of electric field lines crossung the electric field per unit time called flux of electric field .