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Positive charge

  1. Oct 25, 2013 #1
    I've just recently learned that protons do in fact have a charge, I was wondering if someone could explain this, as far as applying a positive charge, some real world examples. I've always studied current as a flow of electrons, never heard of a flow of protons before and have no idea what it would be used for. Thanks
     
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  3. Oct 25, 2013 #2

    CompuChip

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    That's because protons are fairly big, compared to electrons, and are usually confined to the nuclei of atoms (together with the neutrons that make up the nuclei). Electrons, in the "classical" picture, kind of whizz around the nucleus in a relatively big cloud, and it's easy to "knock" them off. Separating the particles that make up the nucleus usually takes more effort. Usually, positive "particles" are not protons, but complete nuclei of atoms with one or more electrons missing*. These "stripped" atoms are called ions (http://en.wikipedia.org/wiki/Ion).

    * The exception is the hydrogen atom, which only consists of one proton and one electron, so if you strip the electron you automatically are left with just a proton.
     
  4. Oct 25, 2013 #3

    dlgoff

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    Actually, in an Intrinsic Semiconductor, both electrons and the holes (absent of electron) contribute to the current.

    intrin2.gif
     
  5. Oct 25, 2013 #4

    AlephZero

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    Actually, electric current is usually not just "a flow of electrons", except in metals.

    You might want to "unlearn" some more misconceptions about electricity from here: http://amasci.com/miscon/elect.html

    True, but "holes" don't conduct electricity because of the movement of protons.
     
  6. Oct 26, 2013 #5

    dlgoff

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    True but the OPs thread title is Positive charge. I figured a little extra knowledge would be good.
     
  7. Oct 26, 2013 #6

    sophiecentaur

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    Whilst they can be considered as 'existing' holes are a very sophisticated concept and will tend to add confusion to someone who clearly regards the motion of the electrons in a wire as a consideration in electrical theory.

    Electrons, 'carrying' the charge through a metal go, on average, very slowly (1mm/s or so) and their mass is tiny so their kinetic energy is completely negligible - so that particular model is really not helpful. Little bullets shooting along a wire are not the way to look at this stuff.
     
  8. Oct 26, 2013 #7
    Sophie I feel like you're being a bit condescending and I'm just trying to learn. That's why I asked the question
     
  9. Oct 26, 2013 #8

    sophiecentaur

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    Apologies if that's how you see my response. My point is that, trying to view 'electricity' just in terms of electrons moving around in a conductor gets you nowhere fast. Electrons, in the environment of a condensed medium like a metal, do not behave as water or marbles (i.e. 'mechanically') They are, essentially, quantum particlesin those conditions. Yes they do behave as though they 'drift around', according to the Electric Fields but it's almost irrelevant when trying to predict the behaviour of a conductor in a circuit. It's no surprise that you won't find that model pursued in circuit theory texts because it doesn't really take you much further in understanding the topic.
    If you want to see electricity in your own, personal way then that's your choice but you will almost certainly be better off in the long run if you take the 'conventional' approach and then, later on, see where the electron motion thing comes in. I guess what I'm saying is that there is no answer to the "what's real happening" question. That goes for all Science, when you get down to it, actually. Some models just work better than others when you want to progress in Science knowledge.
    If you are trying to learn then it could be an idea not to be too committed to any particular personal approach. The majority of scientists didn't go down one particular road just through whimsy. It's just more fruitful, in the long run.
     
  10. Oct 26, 2013 #9

    UltrafastPED

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  11. Oct 26, 2013 #10

    sophiecentaur

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    In liquids, the positive ions can move about - that's a sort of definition of the distinction between liquid and solid when you think about it. (And there are are many 'half way house' substances.)
     
  12. Oct 26, 2013 #11
    "Negative charge" and "positive charge" are are an abundance or lack of electrons, or represent the direction of flow of electric current. They dont necessarily refer to movement of protons, unless its ions in solution etc.
     
  13. Oct 26, 2013 #12

    sophiecentaur

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    Charge is more fundamental than that, although your view is good enough for everyday life. The electron is not the only charged fundamental particle. For example, quarks carry a charge which is e/3.
     
  14. Oct 26, 2013 #13
    When they dope the semiconductors in transistors, is that a form of chemical reaction?
     
    Last edited: Oct 26, 2013
  15. Oct 26, 2013 #14

    dlgoff

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    I'm glad to see that you are asking this question and willing to delve deeper into the physics of the Solid State. The whole point of my original post was not to confuse you about charge but to, as sophiecentaur has pointed out, show there is more to this than

    I'm no expert in condensed matter physics but you may be some day. :thumbs:
     
  16. Oct 27, 2013 #15

    sophiecentaur

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    'Chemistry' is what is used when they actually do the doping but I don't know whether the definition of a 'reaction' is strictly 'producing a new substance' or not. The etymology is hardly relevant here. Whilst a semiconductor is actually operating, I would not say there is a reaction taking place. Nor is there any movement of positively charged real particles. The 'shuffling' of electrons from one positive site to another can be very much like a positive particle moving about in the semiconductor - which is where the notion of holes comes in. You can treat holes in many ways like positive charges moving around but this much be treated with care and no positive charges flow into the terminals of a semiconductor device from the connecting wires!
     
  17. Oct 27, 2013 #16
  18. Oct 27, 2013 #17
    Doping semicon is a fundamental process for creating a material - it would be at the intersection ( basic levels ) of physics, material science, chemistry and, electrical theory. As such would will find specialists in each filed equally able to work in this filed. Since the devices created - are primarilty used in electrical engineering - the general field of study is in EE .
     
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