Electrostatics is the study of electric charges that are at rest.
- Two Types of Electric Charges
When two bodies rub together, they become oppositely charged. Experimental evidence shows
Charges are classified into two types:
The loss of electrons from a neutral substance produces positive charge.
That is, positive charge indicates an electron shortage.
(ii) Negative Charge: Giving electrons to a neutral substance produces a negative charge. Negative charge indicates additional electrons on a neutral material.
The SI unit of charge is coulomb (C).
- Properties of Charges
(i) Charge Conservation: In an isolated system, the charge is constant. Charge cannot be formed or destroyed; instead, it may be transmitted between bodies.
(ii) Additive Property: An isolated system’s total charge equals the algebraic sum of charges on its component bodies. This is known as the additive property of charges. For a system with three charges (q1, q2, – q3), the total charge (Q) is calculated as q1 + q2 – q3.
(iii) Quantification of Charge: A body’s total charge is the integral multiple of its basic charge, q = ± ne, where n is an integer (e.g., 1, 2, 3).
(iv) Charge is unaffected by motion: A body’s charge stays constant regardless of its velocity, hence charge at rest equals charge in motion.
(v) Like charges repel, whereas dissimilar charges attract.
