a pith ball is first attracted by a charged body and is then repelled after making contact. explain why
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Answer:
A pith ball hangs vertically by a thread. A plastic rod is charged by rubbing with cloth. The charged rod is brought close to the pith ball without touching it. It is observed that the charged rod weaklyattracts the pith ball. This may be surprising – and you are right to be surprised, for the pith ball carries no charge. For the time being we are going to put this observation to the back of our minds, and we shall defer an explanation to a later chapter. Until then it will remain a small but insistent little puzzle.We now touch the pith ball with the charged plastic rod. Immediately, some of the magical property (i.e. some of the electric charge) of the rod is transferred to the pith ball, and we observe that thereafter the ball is strongly repelledfrom the rod. We conclude that two electric charges repel each other. Let us refer to the pith ball that we have just charged as Ball A.