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with flannel or catskin. The amber, the rubber comb, the glass rod, the ebonite rod, etc are said to be charged with electricity. The woollen cloth (in case of amber), silk (in case of glass rod) and flannel (in case of ebonite rod) are also found to be charged with electricity. The electricity developed on bodies, when they are rubbed with each other is called frictional electricity. It is also called static electricity as the charges so developed on a body can not flow from one point to some other point. Two kinds of charges From experiments, it was concluded that frictional electricity is of two types. When a glass rod is rubbed with silk, glass rod is said to have become positively charged. As said earlier, the silk is also found to be charged with electricity. However, the nature of charge on silk is found to be opposite to that one glass and therefore silk is said to have become negatively charged. On the other hand, when ebonite rod is rubbed with flannel the charge on ebonite rod is found to be of same kind as of silk (when glass rod is rubbed with it). Thus, ebonite rod becomes negatively charged. hen rubbed with flannel, while flannel it self becomes positively charged. Historically, charge produced on a glass rod, when rubbed with silk was called viterous and that produced on ebonite rod, when rubbed with flannel, was called resinous. Actually, the concept of positive and negative charges was introduced by Benjamin Franklin. Experiments proved that bodies having same kind of charge repel each other, while those having opposite kinds of charge attract each other. In the table given below, if a body in first column is rubbed against a body given in second column, body in first column will acquire positive charge, while that in second column will acquire negative large : The name of the body, which acquires
Positive charge Glass rod Flannel or catskin Wollen cloth Woolen cloth Woolen cloth
Negative charge Silk cloth Ebonite rod Amber Rubber shoes Plastic object
TAG UET 3179 - Hatala, 2003
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