## Electrostatics

Electrostatics stands for static electricity involving study of charges at rest. These charges are developed on insulators when they are rubbed against each other. The charges are produced due to actual transfer of electrons.

### Quantization and Conservation of charge

1) Quantization of charge

a) Electronic charge can exist only as an integral multiple of charge on an electron(-e).

b) The possible value of electric charge are q= +1e, -1e, +2e, -2e, +3e, -3e .

c) Charge less than the charge on an electron is not possible.

2) Conservation of charge

a) On an isolated system, total electric charge always remains constant.

b) Total charge on a body is equal to the algebraic sum of all the charges present on it. Every atom is electrically neutral as it contains as many electrons as the number of protons in it.

c) When we rub a glass rod with a piece of silk, the positive charge acquire by the glass rod is equal to negative charge acquired by the silk price. Thus charges are produced in equal and unlike pairs.

### An electric line of force

An electric line of force is a path, straight or curved, such that tangent to the path at any point gives us the direction of electric field intensity at that point. No two electric lines of force can intersect each other.

### An equipotential surface

An equipotential surface is that at every point of which electric potential is the same. Some of important properties of equipotential surface are:

1) Electric lines of force are always perpendicular to an equipotential surface.

2) Work done in carrying an electric charge from one point to another on an equipotential surface is zero.

3) The component of electric intensity along an equipotential surface is zero.

4) Two equipotential surfaces can never intersect one another.

For Example:

a) The shape of equipotential surface for a point charge; charged spherical conductor and charged spherical non-conductor is spherical.

b) For an electric dipole, equipotential surface is plane.

c) For an infinite linear charge distribution, equipotential surface is cylindrical.

d) For an infinite sheet of charge, equipotential surface is a plane parallel to the sheet.

### Electronic Flux

Electronic Flux over an area in an electric field represents the total number of electric field lines crossing this area normally. It is represented by E . Electric flux is scalar quantity.