Electric Current as a Fundamental Dimension

As e lained in Chapter 6, based on our understanding of our physical world today, we need seven fundamental or base dimensions to correcdy express the physical laws that govern our world. They are lengdi, mass, time, temperature, electric current, amount of substance, and luminous intensity. Moreover, with the help of these base dimensions we can derive all other necessary physical quanddes that describe how nature works. 

To better understand what the ampere represents, we need to take a closer look at the behavior of material at the subatomic level. In Chapter 9 we esplained what is meant by atoms and molecules. An atom has three major subatomic pardcles, namely, electrons, protons, and neutrons. Neutrons and protons form the nucleus of an atom. How a material conducts electricity is influenced by the number and the arrangement of electrons. Electrons have negarive charge, whereas protons have a positive charge, and neutrons have no charge. 

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