All matter is comprised of protons and electrons. It is the electric force between protons and electrons in the atom that holds it together. Electrical current is the flow of electric charge. Electric currents are present in all aspects of our everyday life, from light bulbs, heaters, radios, televisions, cars, computers, and in all biological systems. In order for an electrical current to flow in a body, a difference in electrical potential must exists in it.
Electric potential is similar to gravitational potential.
When an electric charge moves from a higher electric potential to a lower one, it cause a flow of charge, an electric current. An electric potential difference is therefore needed to cause an electric current. In electrical circuits the symbol represents a resistor. Its unit, the ohm, is given the symbol , the Greek letter omega . Resistance is the ratio of voltage to current.