solution

1) Electric flux is defined as the number of electric field lines crossing a unit area perpendicular to the area.

Electric flux Φ = E.da

2) Electric dipole moment of an electric dipole is the product of its either charge and the length of the electric dipole. It is denoted by p. Its unit is coulomb-meter.
p = q x 2l

3) The dielectric constant of a medium is the ratio of force experienced by two unit positive charges when placed at a unit distance from each other in vacuum to the force experienced by the same point charges separated by the same distance in that medium.

4) Quantization of electric charge:— Any charge exists in discrete lumps or packets of a certain minimum charge (+-)e, where e is the charge of an electron. According to quantization of charge, the charge on a body can be only an integral multiple of the charge on an electron, i.e.,

5) Electric field is defined as a region of space around a charge or a system of charges within which other charged particles experience electrostatic forces.
Electric field intensity is a measure of the strength of the electric field. It is defined as the electrostatic force per unit charge.

6) Electric potential energy of a system of point charges is the total amount of work done in bringing various charges to their respective positions from infinitely large mutual separations. PE = kQq/r

7) Electrostatic potential at a point in the electrostatic field is defined as the work done in moving a unit positive charge from infinity to that point against the electrostatic force along any path. It is a scalar quantity. Potential = kQ/r

8) Capacitance of a capacitor is the measure of the capacity of a device of storing charge.

Capacitance, C = Q/V = Charge/Voltage

9) An equipotential surface is that surface at every point of which, the electric potential is the same.