What is a charge ?

  1. what is a "charge"?

    hi,
    what exactly is a charge? how do you define it? why is a positively charged ion at a higher potential difference than a negatively charged ion? why is work needed to be done on a positively charged ion to move it out of an electric field of another positively charged ion?

    i'm very confused with electricity, and i hope i can understand it better if these doubts get cleared :)

    thanks in advance
     
  2. jcsd
  3. Re: what is a "charge"?

    See this, I think it will shed some light on your questions.

     
    Last edited by a moderator: Sep 25, 2014
  4. Re: what is a "charge"?

    Nobody understands charge. We can only describe it, indirectly.

    In fact, the entire universe is composed of energy, but nobody has the foggiest idea what regulare energy actually is, much less "dark energy" if that exists. That's why physics is great fun. You can make up the most outlandish theory you want and nobody can prove you wrong. They can only present an argument against your theory.
     
  5. Drakkith

    Staff: Mentor

    Re: what is a "charge"?

    I think you should look up the definitions of energy and scientific theory. One cannot simply make up theories, they must have very good reasons.
     
  6. Drakkith

    Staff: Mentor

    Re: what is a "charge"?

    A charge is simply the force produced by a charged particle on other charged particles. Electromagnetic charges have a + and a -, aka postitive and negative.

    A positive ion that is moved out of an electric field of another ion is having work done to it by that ion. Or more accurately both ions repel each other, performing work on each other and transforming potential energy into kinetic energy.

    See here for more info: http://en.wikipedia.org/wiki/Electric_charge
     
  7. Re: what is a "charge"?

    Electric charge is a theoretical given. It is an unexplained starting point for theoretically explaining special effects. Theoretical explanations may or may not be correct. They are educated guesses. No one knows what electric charge is. We do know a great deal about its effects. Those effects are seen as patterns in changes of velocity. We know neither the origin of electric charge or of polarity.

    James
     
  8. Drakkith

    Staff: Mentor

    Re: what is a "charge"?

    Please, don't start this again, you will only confuse the OP and others even more. We have a definition of charge which explains what the OP is asking. I suggest you defer to that unless someone wants to talk about theoretical physics or something.
     
  9. Re: what is a "charge"?

    Third thread in a row, really? And you ask why they get closed down.

    The terms under physics are clearly defined, especially what the OP is asking.
     
  10. Re: what is a "charge"?

    A charge is a coupling constant characterizing the interaction between matter fields with the electromagnetic field.
     
  11. Re: what is a "charge"?

    you can think of charge as where the electric field lines end
     
  12. Re: what is a "charge"?

    thanks for your responses. let me elaborate my question, when we say an electron has a charge of -1.60217646 × 10-19 coulombs, what does it mean? is it like some sort of an energy or a virtual "thing"(or assumption) or is it something you can weigh?
     
  13. Drakkith

    Staff: Mentor

    Re: what is a "charge"?

    The coulomb (symbol: C) is the SI derived unit of electric charge. It is defined as the charge transported by a steady current of one ampere in one second.

    The problem with measuring charge, is that the closer you get to the particle the larger the force is. So instead of just saying the force is X amount at X distance, it was defined by the number of charged particles that move across a point when 1 volt is applied for 1 second.
     
  14. Re: what is a "charge"?

    Charge is just a name to describe the properties of electrostatic interactions. Just like mass, what can you say about mass?

    Positive charges do work when they move closer is due to the electrostatic repulsion between charges. When forces move a distance in the direction work is done. Again you cannot explain why, just like why gravity is always attractive? Yes, you can use quantum mechanics (Relativity also for gravity) and string theory, but still you cannot explain quantum mechanics.

    Coulomb is just a SI unit from convention, derived from Ampere defind by Ampere times second. Again and again you cannot ask why, just like asking what does it mean by I have mass of 60kg. It's just measured using the unit. If you use a banana to describe the charge of a proton, then electron just have -1banana of charge. It's just a relative measure used to compare the property of objects.
     
  15. Re: what is a "charge"?

    it means that that is how many electric lines of force end at that point

    each line can be thought of as having a tension along its length and it repels all other lines.

    all lines must end at charges.

    http://www.google.com/search?q=electric lines of force
    http://en.wikipedia.org/wiki/Line_of_force
     
  16. Re: what is a "charge"?

    OK, here's what WIKI says:
    https://secure.wikimedia.org/wikipedia/en/wiki/Energy

    There doesn't seem to be any "scientific theory of energy."
    Energy is an abstract concept that helps us conceptualize theories based on the results of scientific experiments.
    Theories do one thing and one thing only: they predict future events.
    It's not what you are taught in high school, but that's the truth about theories.

    Nobody has the foggiest idea what energy actually is.
    That's not a theory, it's an opinion.
     
  17. ZapperZ

    ZapperZ 29,987
    Staff Emeritus
    Science Advisor
    Education Advisor

    Re: what is a "charge"?

    Please do not CHANGE this thread into ANOTHER ad nauseum thread on "what is energy?".

    Zz.
     
  18. Re: what is a "charge"?

    OK, sorry.
     
  19. Re: what is a "charge"?

    delete, dupe
     
  20. Re: what is a "charge"?

    "...A charge is simply the force produced by a charged particle on other charged particles. ..."

    Electric charge is not a force. Coulomb's equation defines electric force. Electric charge appears in that equation as a part of that which is believed to produce electric force. Electric charge is not understood and that is why it is one of the indefinable properties of physics along with distance, duration, mass, and temperature.

    James
     
  21. Drakkith

    Staff: Mentor

    Re: what is a "charge"?

    No, do NOT start this again. Charge IS defined in science:
    Electric charge is a physical property of matter which causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative.

    That IS what it is. If you want to talk about what it is or isn't go somewhere else.
     
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