Electric Charge

The phenomena of two objects sticking together can be explained by the notion that objects when rubbed can gain a net electric charge. There are two types of charge, labeled positive ( + ) and negative ( - ), with the following basic property:

• Like charges of the same sign repel each other.
• Unlike charges of the opposite sign attract each other.

Detailed experiments have established the following fundamental characteristics of electric charge:

• Charge is never created nor destroyed - it is conserved.
• Charge always comes in an integral multiple of a basic unit - it is quantized.

This basic unit of charge is conventionally denoted by e :

e = 1.602 x 10^{- 19} Coulombs (C) . (1)

In an atom, the charge on an electron is - e and that on a proton is + e .