**Conservation of electric charges:**

Electric charges (quantity of electricity) is conserved in the same manner as linear
momentum, energy, angular momentum etc. The law of conservation of charge is the basis of
many equations of electricity and magnetism. According to the law of conservation of
electric charge, the algebraic sum of positive and negative charges in an isolated system
remains constant. Conservation of charge does not mean that charge cannot be produced or
destroyed. It simply means that if ever charge is created or destroyed, it will always be in
equal and opposite amounts. For example, when two bodies are rubbed, we get simultaneously
two unlike charges of equal magnitudes.

**Quantization of electric charge:**

It is proved from number of experiments that all charges occurring in nature are positive or
negative integral multiples of certain minimum electric charge. This minimum electric charge
is the magnitude of electric charge on an electron. This fundamental charge to which we give
the symbol e, has the magnitude 1.60210 x 10^{-19} coulomb. So, the charge on an
electron is -e while the charge on a proton is +e. The fact that charges on a proton and on
an electron are numerically equal but opposite in sign has been checked experimentally to an
amazing degree of accuracy namely to one part in 10^{20}.

Any charge q, is given by

q = ne

where n = 1, 2, 3, ....

When a physical quantity such as electric charge exists in discrete 'packets' rather than in
continuous amount, it is said to be quantised. This fact is referred to as quantisation of
electric charge. When suitably examined on a microscopic scale, most of the properties such
as mass, energy, angular momentum are observed to be quantised.

**Additive nature of charge:**
The total electric charge of a body is equal to the algebraic sum of all the electric
charges located anywhere on the body. While taking algebraic sum, due consideration has to
be given to + or – signs.
If two charges +2q and +3q are taken, then the total charge is +2q + 3q or +5q. Similarly,
if two charges +2q and –3q are taken, then the total charge is +2q – 3q or
–q.