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Question
When a glass rod is rubbed with a silk cloth, charges appear on both. A similar phenomenon is observed with many other pairs of bodies. Explain how this observation is consistent with the law of conservation of charge.
Solution
The phenomenon of charging by friction is in complete harmony with the law of conservation of charge. When two neutral objects are rubbed in such a phenomenon, both objects get charged. Before friction, both objects are neutral, that is, their total charge is zero. In all such observations, it has always been found that as much positive charge comes on one object, the same negative charge comes on the other object. Thus, even after charging by friction, the net charge of both objects remains zero.
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