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A question about voltage

  1. Sep 17, 2014 #1
    Hi guys.
    I just want to check my information about voltage if it's right.
    I know that electrons in copper wires move randomly but when we apply a voltage like a battery has two terminals one negative and one positive the electrons are attracted to the positive terminal and move in a speed of millimetres per hour but electric current move at the speed of light and electrons gain kinetic energy like if we have a 6 volt battery it means on columb will gain 6 joules of energy or we have to do work equals 6 joules to move charge from a tetminal to which it is attracted,, and when we apply a higher voltage electrons move in a higher speed and thus increasing the current, is that right ? Please say yes or no???!
     
  2. jcsd
  3. Sep 17, 2014 #2

    jim hardy

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    Wow.

    I think you have already answered your question.
    That long long sentence is too long a train of thought for me to wrap my feeble mind around - by the time i get to the caboose i've lost the locomotive.
    Try re-typing your problem statement as a series of one liners, one thought per line.
    Here's first two:


    It's natural to want an immediate answer. Step by step thinking is the way to get one.

    old jim
     
  4. Sep 17, 2014 #3
    [Edit]
     
    Last edited: Sep 17, 2014
  5. Sep 17, 2014 #4

    f95toli

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    No, not really.

    It is not at all helpful to think of movement of electrons when trying to understand concepts like current and voltage in circuit theory. Yes, ultimately these concept do of course involve electrons; but the actual physics is extremely complicated and involves a fair amount of quantum mechanics (and you can certainly not think about electrons as classical objects).

    The one exception to this "rule" is if you are doing something in electrochemistry since you are then can have actual charge carriers (ions) moving around in a solution; but this is much easier to explain than transport in solids.
     
  6. Sep 17, 2014 #5
    Why concepts of electricity are so ****ing complicated
     
  7. Sep 17, 2014 #6
    Please a simple explanation
     
  8. Sep 17, 2014 #7

    jim hardy

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    Yes, ....... i think.

    Here's the problem with run-on sentences:

    9182UUU1Y7L._SL1500_.jpg

    I'm not at all sure that what i think i read is what you think you wrote. That's why i suggested rewriting your statement.
     
  9. Sep 17, 2014 #8

    sophiecentaur

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    The actual concepts are not that complicated - it's just applying them in real situations, that's the problem.
    But why do you presume that there is a "simple explanation"? Most things in Science are, in fact, very complex (most things in life, in fact). The great danger is in oversimplifying stuff to such a degree that the explanation becomes useless. It ceases to be Physics and becomes 'playing around'.
    I would say that there is very little point in attempting to get a grasp of electricity without being prepared to do the simple maths. Even at the level of wiring bells and buzzers, there is no way to explain some simple faults without a quantitative knowledge of how the Currents and Votages are related. I don't mean that you need calculus from the start but simple algebra for rearranging equations is pretty much essential if you want to avoid elementary misconceptions (like "current takes the easiest route" and other nonsense).
     
  10. Sep 18, 2014 #9

    f95toli

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    Concepts of electricity are not that complicated; it is the microscopic details of current transport that are difficult to explain unless you have a very good (graduate level) understanding of solid state physics. Fortunately you do no need to understand those details in order have good grasp of circuit theory (i.e. what we usually mean by current and voltage). I'd say 95% of all electrical engineers do not know the first thing how electron transport in solids actually work (an it is not included in the curriculum if you study EE at university); but then you'd also find that 95% of solid state physicists wouldn't know how to design a useful electrical circuit. They are simply different types of understanding.

    Analogy: Trying to understand electricity by thinking about electron movement would be a bit like learning to repair cars by studying organic chemistry in the mistaken belief that you need to understand the details of combustion in order to repair an engine; you simply do not need to that level of detail.
     
  11. Sep 18, 2014 #10

    sophiecentaur

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    I am going to get on my hobby horse here. School is often to blame for the fashion of trying to 'explain' everything microscopically - whether it's Photons or Electrons. Kids leave school thinking that using those two words is essential in any explanation. It's the fault of the (devisors of the) Curriculum and the poor level of Maths of many (most?) teachers. The bulk behaviour of things is actually very hard to model by arm waving, which is why Hooke's Law, Ohm's Law etc. are used whenever possible. But those laws are very abstract, despite the initial concrete appearance, being based on Maths. You can't wave your arms about a value of Resistance so the temptation is to launch off into a happy flappy rigmarole about pushing and resisting. Total confusion there and students have to forget all that before moving on.
     
  12. Sep 21, 2014 #11
     
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