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We say that a body is negatively charged when it has excess electrons otherwise say positively or uncharged. We also say that electrons are negatively charged. By the above statement, it has more electrons. Doesn't this contradict with our definition or is there another definition of charges in case of electrons?

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  • $\begingroup$ Well using your definition it does have an excess of electrons; there are no other counterparts to neutralize it so there is an excess of exactly 1 electron? $\endgroup$ Commented Mar 15, 2015 at 17:10
  • $\begingroup$ When we say excess we must surely compare, so what are we comparing this 1 electron of ours? $\endgroup$
    – Socre
    Commented Mar 15, 2015 at 17:12
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    $\begingroup$ Typically you're comparing to the number of protons (which are immobilized in the nuclei of the atoms in the material). $\endgroup$
    – The Photon
    Commented Mar 15, 2015 at 17:14
  • $\begingroup$ In this case it's 1 electron with 1 proton, it doesn't make sense, I'm confused? $\endgroup$
    – Socre
    Commented Mar 15, 2015 at 17:26
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    $\begingroup$ That would be a balanced charge. If you had 1,000,000 protons and 1,000,001 electrons, that would be one excess electron. $\endgroup$
    – The Photon
    Commented Mar 15, 2015 at 17:35

1 Answer 1

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Think of charges as a bunch of $+1$s (protons) and $-1$s (electrons). It doesn't matter how many $0$s (uncharged particles) we have because $0 + 0 + 0 + 0 +... +0 = 0$.

Now in most cases it's pretty difficult to change the number of $+1$s a body has, so we can see if it has more $-1$s than $+1$s to know if it's negatively charged or not. Let's call the "charge" of a body $Q$.

If we have $m$ $-1$s on the body and $n$ $+1$s on the body, then

$$ Q = 1 - 1 +1- 1 +... +1 = n -m $$

So if $n > m$ then $Q$ is positive so the body is "positively charged." If $m < n$ then $Q$ is negative so the body is "negatively charged." If $m = n$, then $Q = 0$ and the body is "electrically neutral."

It doesn't matter how many $+1$s and $-1$s. Even if we have 10 billion $+1$s, if we have 10 billion and 1 $-1$s, then $m > n$ and the body is "negatively charged."

Any questions?

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  • $\begingroup$ This is a rigorous definition of charges, and I understand where your getting at. Here is a counter example, if you have a material 'x' which has 5 electrons and 3 protons. It has a net charge of 2. Now the material 'e' which I'm talking about is an electron which is an entity by it self. This electron has no proton inside it. The proton 'p' is considerd as another material. So your definition works for materials containing protons and electrons $\endgroup$
    – Socre
    Commented Mar 15, 2015 at 17:55
  • $\begingroup$ In that case, $n = 0$ and $m=1$. An electron has no protons inside of it, but an electron does contain 1 electron. $\endgroup$
    – trifork
    Commented Mar 15, 2015 at 17:59

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