It was experimentally demonstrated by
Millikan in 1912 In the International System (SI) of Units, a unit of charge is called a
coulomb and is denoted by the symbol C A coulomb is defined in terms
the unit of the electric current which you are going to learn in a
subsequent chapter In terms of this definition, one coulomb is the charge
flowing through a wire in 1 s if the current is 1 A (ampere), (see Chapter 1
of Class XI, Physics Textbook , Part I)