The Naked Scientists

The Naked Scientists Forum

Author Topic: Can we do without Magnetism?  (Read 1622 times)

lyner

  • Guest
Can we do without Magnetism?
« on: 02/07/2009 11:37:43 »
There has been a lot of talk on these fora, recently, involving the importance of Magnetism  in the Universe.

I can't remember whether this has been mentioned recently but there is an alternative way of looking at electric currents which accounts for so-called Magnetic attraction in terms of the Coulomb Force (electrostatic attraction and repulsion).
It all depends on the relativistic (Lorenz) effects of moving electrons - even though they are only traveling at a few mm/s.

There are many links which tell the story more fully than the following but what it boils down to is this.

The moving electrons in a wire will appear to a stationary observer, to be closer together (i.e. more densely packed) because of the Lorens contraction. Imagine a wire, laid parallel to this wire. It will have an equal number of + and - charges  so, despite the apparently different densities of charges in the current carrying wire, there will be no net force on the second wire; the repulsions and attractions will all balance out. But, once a current starts to flow in the second wire, (let's say in the same direction as in the first wire) the relative speeds of electrons in the two wires will be the same but the electrons will 'see' more densely packed protons in the other wire. This will produce a force of attraction between the wires. Likewise, the protons in each wire will 'see' a greater density of electrons in the other wire - also producing an attractive force.

When the currents flow in opposite directions the resulting force (by a similar argument) will be repulsive (the electrons will 'see' more densely packed electrons in the other wire).
How can this work for electron drift speeds of a few mm/s (10-11 of c)? The Lorenz contraction is very small, of course, but there will be an awful lot of electrons involved (1023 per mol of the metal). It all adds up to a significant force.
Doing the calculation this way will predict the same force that the magnetic calculation will give you.
So you don't need Magnetism at all.
See below.
http://galileo.phys.virginia.edu/classes/252/rel_el_mag.html
http://www.newton.dep.anl.gov/askasci/phy00/phy00993.htm
http://skepticsplay.blogspot.com/2007/12/relativity-electrostatics-magnetism.html


 

Offline LeeE

  • Neilep Level Member
  • ******
  • Posts: 3382
    • View Profile
    • Spatial
Can we do without Magnetism?
« Reply #1 on: 02/07/2009 16:23:33 »
I quite like this model.  Thanks for pointing it out.
 

lyner

  • Guest
Can we do without Magnetism?
« Reply #2 on: 02/07/2009 16:30:24 »
I think it's amazing how a  small effect, which one could so easily dismiss, adds up when there are so many individual particles involved.
Nothing is obvious!
 

The Naked Scientists Forum

Can we do without Magnetism?
« Reply #2 on: 02/07/2009 16:30:24 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums