Introduction

Electrical network is an apparatus that includes sources of energy, connecting wires and components. An electrical circuit functions to transfer energy. The source of energy may be a voltage source or current source and dependent and independent sources. The components may be passive or active. 

Charge

An atom is composed of a positively charged nucleus which consists of neutron, positively charged protons and surrounded by negatively charged electrons. An atom with equal number of electrons and protons is referred to as an electrically balanced or neutral atom. An electrically balanced atom becomes a negative ion if it receives one or more electrons and becomes a positive ion if it loses one more electron. 

An electric charge (represented by a letter q or Q) occurs when atoms in a matter contain unequal electrons and protons, The charge of an isolated conductor resides at the conductor surface. When a charge is added to a conductor, it distributes uniformly all over the surface.

An electron has negative charge and has a charge of 1.6021x10-19 C. The unit of charge is coulomb (C), named after the scientist Charles Augustin de-Coulomb. Electron charge is very small and the charge of 6.24x1018 electrons added together is one coulomb. The coulomb is defined as the quantity of electricity transported in one second by a current of one ampere. 

Example:

The electric charge (Q) carried by __________________ electrons represent one coulomb,
a) 1.6021 x 10^-19            b) 6.24 x 10¹⁸
c)  1.6021 x 10¹⁹            b) 6.24 x 10^-19