CHAPTER 1 THE FUNDAMENTALS OF ELECTRICITY lectricity is a form of energy associ ated with the atomic particles called electrons and protons In particular electricity involves the movement or accu mulation of negatively charged electrons in relation to positively charged protons The world's modern economies with their industrial transportation and com munication systems were made possible by electricity Old energy forms such as water and steam imposed limitations on production limitations on where goods could be produced and on how much could be produced Electricity has few such lim its it can go anywhere even far into space The development of electricity has resulted in the total transformation of civili zation It brings power into homes to operate lights kitchen appliances television sets radios furnaces computers garage
THE FUNDAMENTALS OF ELECTRICITY and more So common are its uses that one cannot imagine today s world without it Streets would not be lit Telephones would not work Storefronts and factories would be dimmed Electrical forces are also responsible for holding body cells together in the shape they have In fact electrical forces are fun damental in holding all matter together As printed words are being read electric cur rents speed along nerve cells from eye to brain The effect of an electric current can be seen in the flash of lightning between thundercloud and Earth as well as in the spark that can be produced when one walks on a carpet in a dry room STATIC ELECTRICITY AND ELECTRIC CHARGE Understanding electricity begins with describing its effects One way to begin is to examine interactions that occur when electricity is at rest in a form called static electricity Static electricity can be seen at work when hair is combed on a cold dry day As the comb is pulled through strands of hair stand out stiffly Some kind of force II
ELECTRICITY This barber employs the novel technique of cutting a customer's hair after it has been charged with static current making it stand on end and thus presumably easier to cut General Photographic Agency Hulton Archive Getty Images 12
THE FUNDAMENTALS OF ELECTRICITY seems to pull the strands upward toward the comb To understand the nature of this force it is necessary to know something about the concept of electric charge and the structure of atoms Simple experiments can illustrate how electric charge works If a glass rod is rubbed with silk and touched to a small sphere of aluminum foil suspended by a thread the sphere moves away from the glass rod The rod and sphere repel each other If the pro cess is repeated with a second sphere and the spheres are brought near each other they too repel If a plastic rod is rubbed with wool and brought near either sphere the spheres move toward the plastic rod These objects attract each other If two new alumi num foil spheres are touched to the plastic rod they are repelled by the plastic as well as by each other But they are attracted to the glass rod and the spheres touched by the glass rod These experiments can be explained by a two charge model Rubbing the glass with silk causes the glass to acquire a positive charge When touched to the spheres it shares some of its positive charge with the spheres and these objects repel Rubbing the plastic with 13
