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When we rub our hairs with a comb, and then try to attract small pieces of paper, they're attracted by the comb. The pieces of the paper were not electrified before they were attracted. Then they might be neutral. Why does the comb attract the pieces of the paper if they're neutral, and have no influence of a specific charge on them (Pieces of paper).

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6 Answers 6

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This is because the neutrality of polarity can be changed by electric field in this case. When you create - charge in the comb and you expose the pieces of paper to the electric field created by the charge, you will polarise them so that the part closer to the comb will be + and the other will be -. Explaining image - the brush and some papers

Here, see the electric field. The same polarities do not like each other: enter image description here

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    $\begingroup$ This does not answer the most important thing -- why are there more negative charges in the comb in the first place? $\endgroup$ May 7, 2013 at 0:11
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    $\begingroup$ Unfortunately, this question is not being asked by the OP. $\endgroup$ May 8, 2013 at 13:45
  • $\begingroup$ @PricklebushTickletush Search for "triboelectric series". $\endgroup$ Oct 5, 2020 at 13:00
  • $\begingroup$ This answer is incorrect. $\endgroup$
    – Richard
    Jan 9, 2021 at 11:52
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As none of the answers posted earlier are correct, I am just reproducing what Feynman had explained (The Feynman Lectures in Physics, Vol. 2, Section 10.5):

A surprisingly complicated problem in the theory of dielectrics is the following: Why does a charged object pick up little pieces of dielectric? If you comb your hair on a dry day, the comb readily picks up small scraps of paper. If you thought casually about it, you probably assumed the comb had one charge on it and the paper had the opposite charge on it. But the paper is initially electrically neutral. It hasn’t any net charge, but it is attracted anyway. It is true that sometimes the paper will come up to the comb and then fly away, repelled immediately after it touches the comb. The reason is, of course, that when the paper touches the comb, it picks up some negative charges and then the like charges repel. But that doesn’t answer the original question. Why did the paper come toward the comb in the first place?

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The answer has to do with the polarization of a dielectric when it is placed in an electric field. There are polarization charges of both signs, which are attracted and repelled by the comb. There is a net attraction, however, because the field nearer the comb is stronger than the field farther away—the comb is not an infinite sheet. Its charge is localized. A neutral piece of paper will not be attracted to either plate inside the parallel plates of a capacitor. The variation of the field is an essential part of the attraction mechanism.

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  • $\begingroup$ Could you please explain how does this differ from the explanation that I posted? I cannot see the distinctions between your and my answer. If my answer is really incorrect, if you pointed the exact distinctions it would be really helpful. $\endgroup$ Jan 9, 2021 at 19:04
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Basically, when an electrification takes place, electrons are not created but they are transferred..... in the case of comb attracting tiny tiny bits of papers when rubbed with dry hair is because electrons from the dry hair gets transferred to the comb and now the comb induces a dipole in the bitties of paper and the paper gets attracted...

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Due to the induced dipole they get attracted to the electrified comb i.e, negative charge.

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As the hair have negative charge it get attracted to the positive charge of the comb. When we take comb to the bits of paper then it get induced

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    $\begingroup$ Hi user57145, this is a pretty incomplete answer. Can you expand this to explain better? $\endgroup$ Aug 12, 2014 at 14:40
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when we comb our hair our comb get charged and when we bring comb near pieces of paper the charge get induced on paper.[induced means when we bring any charged partical towards neutral thing ,the neutral thing develop opposite charge on them]

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