History of Electricity
In 1660 Otto von Guericke invented a machine for producing static electricity. It was a ball of sulfur that was rotated by a crank with one hand and rubbed with the other hand. The Van de Graaf generator is a highly developed descendant of that and other machines. It is sometimes used as a particle accelerator. Robert Boyle found out that attraction and repulsion were jointed and that electric force was sent through a vacuum. Stephen Gray distinguished between conductors and nonconductors. C. F. Du Fay recognized two kinds of electricity and Benjamin Franklin and Ebenezer Kinnersley later named them positive and negative. Also during the early 1700s, Frenchman Charles Dufay observed that there are two kinds of electric charges. He found that opposite kinds attract each other while similar kinds repel. He called one kind vitreous and the other kind resinous.
Benjamin Franklin's theory was that electricity was a kind of fluid.
According to his theory, when two objects are rubbed together, electric fluid flows from one object to the other. The object that gains electric fluid gets a vitreous charge, which Franklin called positive charge. The object that loses electric fluid gets a resinous charge, which Franklin called negative charge. Franklin demonstrated that lightning is a form of electricity. In 1752, Franklin did his kite experiment.
The electron theory, the basis of modern electrical theory, was first advanced by Dutch physicist Hendrik Antoon Lorentz in 1892. American physicist Robert Andrews Millikan accurately measured the charge on the electron in 1909.
An electron is an elementary particle carrying a unit charge of negative electricity. The electron is one of the basic elements of matter. Ordinarily there are enough negative electrons to balance the positive charge of the nucleus, and the atom is neutral. If...