magnetic fields, electric fields and photons

Discussion in 'Physics' started by wes, Mar 31, 2008.

  1. wes

    Thread Starter Active Member

    Aug 24, 2007
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    hey i have always wondered what a magnetic field is??? i mean i know a electric field is electrons and this give a electrical charge and photons are the particles of light(which is also a wave) and that is called electromagnetic radiation. but what is a magnetic field, i know it is created by electrons moving and when thier all in one direction, you have a magnet, but what is the field, is it composed of photons(wave), just like how a electric field is electrons, are the electric and magnetic fields the same thing but just in differnt forms or is it some other particle or wave or both (electrons are also waves) . i am really confused as to what it is, i have checked google and they really dont tell you, do we not exactly. well any info would be great. thx
     
  2. Dave

    Retired Moderator

    Nov 17, 2003
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    Have a look at something called "magnetic monopoles" (we had a discussion on this subject just this last week). This is a theoretical particle that is analogous to electric charge, but obviously "magnetic charge". It must be stressed that it is theoretical and has not be confirmed one way or the other.

    Other than that, all you need know is that the magnetic field is a field that exerts the magnetic force on electric charge and dipoles.

    Dave
     
  3. Mark44

    Well-Known Member

    Nov 26, 2007
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    An electric field is produced by a flow of electrons, but otherwise they're two different beasts, if my memory of physics serves me. I remember something about how light is able to travel through empty space with a combination of electric and magnetic fields pulsing away, with nary an electron around. Before the time of Maxwell, I think it was, the thinking was that a wave required a medium in which it could travel, similar to the way that water waves travel through water or sound waves through air. Physicists of that time posited that light travelled from the sun and moon and stars via a substance they called ether (unrelated to the anesthetic liquid of many years ago).
     
  4. Dave

    Retired Moderator

    Nov 17, 2003
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    Scientists like the idea of symmetry in nature. For electric charge some would like to thing there is a magnetic equivalent; hence the theoretical magnetic monopole.

    Dave
     
  5. studiot

    AAC Fanatic!

    Nov 9, 2007
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    As Mark says, No sir.

    Sorry, Mark, No sir. (It's true but only part of the truth.)

    Electrons produce an electric field, whether they flow or not. There is even a branch of Physics we call Electrostatics.

    Electrons in motion produce a magnetic field. Their motion does not affect the electric field.

    In fact you do not need electrons at all to produce an electric field. An electric field is produced in the space around any accumulation of electric charge. This charge may be negative (eg an electron, negative ion etc) or positive (eg a proton, positive ion etc).

    The exact nature of 'charge' has not yet been fully explained by physics, so we describe it by its effects.

    The principal effect is that a second charge experiences a physical force when it is within the electric field produces by a first charge. We can observe and measure this force and deduce physical laws about the effect.

    Magnetic fields are associated with electric fields.

    If the charge generating the electric field does not move the associated magnetic field is zero.

    If the electric charge moves we can detect (and measure) a second force, at right angles to the force produced by the electric field, on certain particles. We call this the magnetic field.

    I say certain particles because the field is there but only appears to act on certain particles, we call magnetic materials. Just as the electric field only acts on particles which possess a net electric charge.

    I say appears to act because magnetism acts on all particles but is an aggregate effect. This means that the magnetic field acts individually on all the aorticles that make up a body. We only see an effect if all the individual actions 'line up' to some resultant, rather than cancelling each other out. Materials with the former property we call magnetic and with the latter non-magnetic.
     
  6. Mark44

    Well-Known Member

    Nov 26, 2007
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    Studiot,
    I bow to your superior wisdom...
     
  7. wes

    Thread Starter Active Member

    Aug 24, 2007
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    thx but i just wondered if we know exactly what a magnetic field is and why it is so differnt from a electric filed yet they both come from the same thing just one is produced when the particle is in motion ( proton, ion , electron )
     
  8. Dave

    Retired Moderator

    Nov 17, 2003
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    We can see the effect without truly understanding the cause. We know that magnetic fields surround electric currents, changing electric fields and magnetic dipoles.

    I gestured to a possibility previously that draws analogies with electric charge: http://en.wikipedia.org/wiki/Magnetic_monopole

    Dave
     
  9. studiot

    AAC Fanatic!

    Nov 9, 2007
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    So does everybody else, but take heart

    Just such wondering (about a compass needle) led a small boy to grow up and discover the theory of relativity.
     
  10. wes

    Thread Starter Active Member

    Aug 24, 2007
    242
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    well thx and hopefully one day we will know exactly what it is then
     
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