|MadSci Network: Physics|
Dear friend, The first rule to be mentioned before the answer is the famous Franklin's model of electric charge and matter. This rule says that the charge can neither be created nor destroyed; it can only be transferred. This model includes more points (law of conservation of charges) : 1-Matter contains two types of electric charge, called positive and negative. Uncharged objects have equal amounts of each type of charges. When objects are charged by rubbing, electric charge is transferred from one object to another. After this rubbing process, one of the objects has excess positive more than the other. 2-As you know, alike charges repel, and unlike charges attract. So simply, the answer to your question is that the charges are not induced on the rubbed rod; they are just transferred from the cloth you are rubing with, whether that was wool, cotton, or silk. This phenomenon was described by both Franklin and Coulomb. Coulomb was more accurate that he reached to a law linking the force between two charged bodies. He used a device called Coulomb's torsion balance. Since your question was specific to glass, I think this is enough. However, the case differs if we have a conductor that we want to charge. Waiting for feedback, Moataz Attallah Undergraduate Mechanical Engineering The American University in Cairo-Egypt firstname.lastname@example.org
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