Electric is a basic quantity. The property of electric charge is much the same with certain subatomic particles, and experimental evidence leads us to the conclusion that there are two types of charges. They are designated as positive ( + ) and negative ( - ) for difference. All matter, according to modern theory, is made up of tiny particles called atoms, which are composed in part of negatively charged particles called electrons, positively charged particles called protons, and neutral particles that carry no electric charge, called neutrons.

All three particles have a certain mass, but only electrons and protons holds electric charges. The magnitudes of the electric charges on the election and the proton are equal, but their natures are unlike, as expresses by the plus and minus sign. When we have the equal number of electrons and protons, the total charge is zero, (same number of positive and negative charge of equal magnitude), and we have an electrically neutral situation.

The unit of electric charge is called the coulomb (C), and was named after Charles Coulomb, the French scientist who studied electrical effects. Electric charge is frequently designated by the letter q. A + q indicates that an object has an overflowing number of positive charges, or more proton that electrons. A - q indicates an overflowing of negative charge, or more electrons than protons.

When charge "flows," or is in motion, we say we have an electric current. Current is defined as the time rate of flow of electric charge. It is measured in units of amperes, names after Andrè ampère (1776-1836), one more early French investigator of electricity. One ampere (A) is equivalent to a flow of one coulomb of charge per second. In cymbol notation we relate electric current, commonly designated by the letter I

In the formula above, where I is the electric current, measured in amperes. And q is the electric charge flowing past a given point, measured in coulombs. And t is the time for the charge to move past the point, measured in seconds.

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