Charge is a basic property associated with the elementary particles and its definition is as difficult as the definition of mass or time or length. We can measure the charge on a system by comparing it with the charge on a standard body but we do not know what exactly it is that we intend to measure. The SI unit of charge is coulomb abbreviated as C. 1 coulomb is the charge flowing through a wire in 1 s if the electric current in it is 1 A. The charge on a proton is
e = 1.60218 × 10-19 C
The charge on an electron is the negative of this value.
