In everyday life, we can listen to the radio, watch television, use the refrigerator and electric irons. Have you ever watched an electric circuit in radio, television, refrigerator, or iron? Have you ever wondered why radio, television, refrigerator, or the board can function? The use of these tools require electricity. Electric currents occur because of the transfer of electric charges. Electricity can be divided into static electricity (electricity is not flowing) and dynamic power (electricity flows). Electrostatics static electricity or electricity is part of the science that studies the properties of electric charge.
We cut a solid body, for example copper, into sections which are always smaller, and thus in the end we get an atom. The word atom comes from the Greek and means “can not be divided”. In some time later before the proof can be found through experiments that solid objects composed of atoms. Of the many results of experimental physicists such as Rutherford and Bohr concluding that an atom should be structured similar to our own solar system (Figure 1.4).
Figure 1.4 The model of the solar system
From the description of this model of the atom consists of a nucleus of an atom and the sun around the nucleus in circular or elliptical trajectory of circulating planets as electrons. Trajectory around the nucleus and form something called the electron shell (Figure 1.5).
Figure 1.5 Model atom
The electrons in the outer shell are called valence electrons, they located the farthest from the core and therefore it’s best to be influenced from outside.