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How does electrical energy perform work?

  1. Sep 9, 2012 #1
    Sorry if the title is slightly misleading, but I'm having a hard time trying to develop a better understanding of electric current and electrical energy. Basically, I understand that, say for example, a potential difference across a circuit creates an electric field, which in turn causes the electrons in a copper wire (for this example) to move in the direction of the electric field. The higher the difference, the greater the force that acts on the electrons.

    Here is where I have some trouble- what actually IS electrical energy? Like, I understand that the electrons start to move (very slowly), but what actually performs work? It's not the movement of the electrons, as that would be kinetic energy, and the mass of an electron is extremely small, so collisions with atoms wouldn't amount to much, right?.

    I guess a better way to phrase my question(s) would be "What is it about the flow of electrons that has the ability to do work, whether it be light a light bulb, create heat, etc.? Why does a flow of electrons create electrical energy? How is this energy then put to a practical use?" If my question's reveals misunderstandings, please by all means point it out, I've been toying with this for awhile now.

  2. jcsd
  3. Sep 9, 2012 #2
    As the electrons/holes move through the solid, they may scatter (by changing their pseudomomentum and/or band index) off of any of the following:
    • impurities in the perfect crystal structure
    • thermal fluctuations of the ions from their equilibrium positions in the lattice - the quasiparticles of which are called phonons
    • other electrons
    • various other collective modes described by different quasiparticles
    In all of these scattering events, the energy of the directed motion of the electron through the solid is converted in other forms of energy corresponding to one of the above excitations. The temperature of the solid, for example, corresponds to a higher phonon density. A polariton is a light quantum proagating through the solid. Furthermore, the incident momentum flux causes mechanical pressure on the ionic lattice. Thus, any deflection of the electron beam in an external magnetic field would cause a subsequent deflection of the current-carrying wire.
  4. Sep 9, 2012 #3


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    Your questions are ones that many have when they realize that electrical energy and current flow via electrons have a cause and effect that's not what's commonly taught in most basic electronics classes.

    This is a standard link that's helpful: http://amasci.com/miscon/elect.html

    and this https://www.physicsforums.com/showpost.php?p=1668323&postcount=27
    Last edited: Sep 9, 2012
  5. Sep 9, 2012 #4
    Electric motors (which convert electric energy into mechanical energy) take advantage of the fact that and electric current also produces a magnetic field. You can use some magnetic materials to get mechanical work from this field.
  6. Sep 10, 2012 #5
    Thanks for the responses, they have been helpful!

    @nsaspook- Thanks for that link, it's extremely helpful, and although I still have to work on my understanding of electromagnetic energy (at least I have a name to what I'm trying to figure out, rather than the ambiguous "electrical energy"), I'm making some good steps in FINALLY understanding what's going on in circuits (those circuit diagrams he had which showed E, B, and electromagnetic energy fields were great, I just hope someone now comes around and makes a 3-d diagram, one which you could overlay any combination of the 3 fields over the circuit, to get a better feel for it.) It has also helped me solidify some concepts that needed polishing. Hopefully I'm on my way to developing a better intuitive understanding of electromagnetism!
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