⊛ Charge is the fundamental property associated with matter due to which it produces and experiences electric and magnetic effects.





⊛ There are two types of charge : positive and negative. This categorization has been made just to distinguish the nature of interaction.





⊛ SI unit of charge is coulomb (abbreviated as C).





⊛ Charge is a scalar quantity which means it can be added or subtracted algebraically.





⊛ Charge resides on matter i.e. mass. Alternatively, without mass the existence of charge is not possible though mass can exist without charge. Thus, presence of charge itself is a convincing proof of existence of mass. This also follows that in the process of charging, mass of the body changes.





⊛ Charge is transferable. If we put a charged body in contact with another body, then charge can be transferred to another body.





⊛ Total charge of an isolated system is always conserved i.e. charge can neither be created nor destroyed. This holds good in all types of reactions either chemical or nuclear.





⊛ Unlike mass, total charge of a body does not depend on its speed i.e. charge is invariant. On the other hand, mass of a body is dependent on its speed (Greater the speed, greater is the mass) according to Einstein’s relativity theory.





⊛ Like charges repel while unlike attract.





⊛ Accelerated charge radiates energy in the form of electromagnetic waves.





⊛ Charge is quantized. The quantization of charge is the property by virtue of which all free charges are integral multiple of a basic unit of charge represented by e (where e = ± 1.6 × 10⁻¹⁹ C). This value is the minimum possible quantity of charge which can exist individually and hence is known as the quantum of charge.





Thus if net charge on a body is Q, it is expressible as Q =

±ne, where n = 1, 2, 3, 4...