Conservation of charge is the property by virtue of which total charge of an isolated system always remains constant.

for example, when we rub 2 bodies, what 1 body gains in charge, the other body loses the same charge. Thus it is not possible create or destroy net charge carried by any isolated system.

A neutron turns in to a proton and an electron. The proton and electron thus created have equal and opposite charge. The total charge is zero before and after the creation. Thus charges can be created or destroyed in equal and unlike pairs only.


The force of interaction between any two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.

Suppose two point charges q1 and q2 are separated in vacuum by a distance r.

 According to coulomb’s law

Where k is electrostatic force constant

The value of electrostatic force constant k depends on the nature of medium separating the charges, and on the system of units.

When the charges are situated in free space (air/vacuum). Then in c.g.s. system.  k = 1

In S.I., k = 9 × 109 N m2c-2