1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why the magnetic field is creating around electrons?

  1. May 9, 2007 #1
    Why magnetic field is creating around electrons?

    Why magnetic field is creating around electrons when there is current in coductor? Why the magnetic field is not creating around protons?
    Last edited: May 9, 2007
  2. jcsd
  3. May 9, 2007 #2
    I don't understand what you're asking. Can you rephrase the question?
  4. May 9, 2007 #3
    Now look the question.
  5. May 9, 2007 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    The 'speed' of electrons in a conductor cannot be mixed with the ones that are free. This is because electrons in a conductor can be approximated as an electron GAS, and thus, undergo collisions not just among themselves, but with the ions of the conductor. The end result is that the electrons have a CONSTANT DRIFT VELOCITY when there is an applied potential or field to the conductor.

    This will not be true if these are free electrons since the Lorentz force will cause an acceleration.

    BTW, you changed your question rather drastically. You should think things through a bit more before posing such questions.

  6. May 9, 2007 #5
    Can you answer me on the first question?
  7. May 9, 2007 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    No, because the question doesn't make sense, and you are apt to CHANGE the damn thing again. This is an annoying habit that you need to stop, or else the thread makes no sense.

  8. May 9, 2007 #7


    User Avatar

    Staff: Mentor

    Do you mean, why do the electrons in a current-carrying wire produce a magnetic field but the protons do not? It's because the conduction electrons are moving (they have a net nonzero velocity along the wire) but the protons are not.
  9. May 10, 2007 #8
    what is a net nonzero velocity?
    and is the electric field moving?
    does magnetic field create around proton?
    Last edited: May 10, 2007
  10. May 10, 2007 #9
    When something has a net nonzero velocity; it is in motion.
    Last edited: May 11, 2007
  11. May 10, 2007 #10
    Nope, it is not. Though electrons flow through the conductor it has no net electric charge. Actually for every free electron contributing in electric current there is a positively charged ion nearby. The drift velocity of the electron is constant and electrons flow through the conductor uniformly without creating any polarity.
  12. May 10, 2007 #11


    User Avatar
    Science Advisor

    Protons are much more massive than electrons and do not move in a conductor. Since it is the motion of charge that causes a magnetic field, there is no magnetic field cause by protons.
  13. May 10, 2007 #12
    Then how is possible only to create magnetic field around the electron? Why it is not creating around proton?
  14. May 10, 2007 #13
    The origin of the magnetic field is the moving electrons but it is not confined around the electrons, though.
  15. May 10, 2007 #14
    The origin of the magneic field in the wire, is the electric field which is created with motion of the electrons. But the question is, is that electric field moving?
  16. May 10, 2007 #15
    No, motion of electrons inside the wire does not create any electric field as i have stated before.
    Whether stationary or in motion an electron has it's own electric field but it can be cancelled by positive charges standing nearby.
    It is the moving charge (charge and electric field are not same ) which creates magnetic field -nothing more or less.
    Last edited: May 10, 2007
  17. May 10, 2007 #16
    I think you are confused. Look man, moving magnet among some conductor will produce current inside the wire(electro-induction). So the magnetic field created electric field, but also the electric field can create magnetic field. So it is not even logical what u are saying, that just moving of the electrons create magnetic field.
  18. May 10, 2007 #17


    User Avatar
    Homework Helper

    Technically, the field is the sum of moving components, but as each electron leaves one end of of a section of wire, another electron enters the other end, so that the net sum of these tiny fields doesn't move. Since a single electrons contribution to the total sum is so relatively small, the small variations in the electrical field are ignored. It's not practical to worry about what's going on at the atomic level when dealing with classical electical physics of currents and fields, which involve huge numbers of moving electrons.

    Note that free electrons don't flow smoothly. They move at very high speed, almost randomly in all directions, occsionally being captured by atoms causing the release of a different electron. The movement is almost random, but there is a net flow of electrons when there is current. This net flow is extremely slow compared to the actual speed of the free moving electrons.
    Last edited: May 10, 2007
  19. May 10, 2007 #18
    There is no electric field to move.
  20. May 10, 2007 #19
    So the magnetic nor the electric field are attached to the electrons right? They are positioned in one place, right?
  21. May 10, 2007 #20
    Electrons have their own individual electric field. Currents exist because the electrons are responding to an external field. It is the external field, not the electric field belonging to the electrons, that is responsible for the flow of charge. Everything that responds to an external electric field has its own.

    Electrons - or any particles, for that matter - do not have their own magnetic field. Magnetic fields don't work that way. What we consider a 'magnetic field' - that responsible for the Lorentz force - is a consequence of moving charges. Magnetic fields are what happens when you observe an electric field in a relativistic reference frame - from the point of view of the moving charge, the electric fields have a different geometry, and so an additional force is present.

    Your suggestion that the fields are 'fixed in place' is, I suppose, true, but I wouldn't feel comfortable describing them that way. There's nothing 'fixing' a magnetic field in place; being constant in space is what a magnetic field is, at least when you have constant current. In other words, saying that the field itself could move is nonsensical; fields don't 'move'; they change in space. If you have a non-constant current, or a current-carrying object moving in space, then yes in a particular fixed position the stength and orientation of the magnetic field will change. But a magnetic field is not bound to any particular object or charge, it is what it is as a consequence of how it is generated.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook