I order to talk about electricity, it is necessary first to talk about the atom. The idea of the “atom” has along history, extending back to about 600 BC, to the time of the ancient Greeks. They believed that all matter was made of atoms. The “atom” infact comes from the Greek word “atomos”, which means “indivisable“. It was not until 1897 that it was discovered that the atom is not indivisable but it composed of even smaller particles. among these particles there is one called the electron
Electrons orbit around the centre or nucleous of the atom, much as the planets in the solar system orbit around the sun. Electron closer to the nucleous are held more tightly than those in the outer orbits. It is the electrons in the outermost orbit of certain kind of atoms that can be made to flow as electric current.
Electron flow easily through certain kind of materials called “conductor”. Many metals, such as silver, copper, gold, and aluminium, are good conductors. Good conductors are used in electric circuits to procide a path for the current.
Other substances procide srong resistence to the flow of the current. These substances are called “insulators”, and are used to confine a current to the desired path. Substances such as hard rubber, glass, wax, and certain kind of plastic are good insulators. Thus, the cord on an electric appliances consist of a piece of wire, generally copper, surrounded by a type of plastic such as vinyl, which is the insultor confining the current to its path.
|extend back to||membawa (kita) kembali|
|indivisible||tidak dapat dibagi|
|is composed of||terdiri dari|
|outermost||yang paling luar|