Do all electric motors follow these two laws?

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  • #26
Simon Bridge
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I'm thinking of Gravity in GR and the Fields of QFT.
In both cases - the "force" is an emergent phenomenon.
In GR the "force" of gravity is a pseudoforce - a product of geometry rather than a Newtonian inertial force.
In QFT the appearance of "force" is the result of lots of interactions via gauge bosons.

Have a look at:
http://www.hep.manchester.ac.uk/u/dasgupta/teaching/Dasgupta-08-Intro-to-QFT.pdf
http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html

But DaleSpam may have other things in mind or a better illustration.
 
  • #27
Dale
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How can Force = 0, while Energy = x. I'm troubled here... how can a field have energy in general, like when a magnetic field or electric field store energy, while forces are zero?
Here is a good page on the topic: http://farside.ph.utexas.edu/teaching/em/lectures/node89.html

In short, the electric field has an energy density proportional to E², and the magnetic field has an energy density proportional to B². So, if you consider a closed region of vacuum there is, by definition, no matter in there and so nothing on which to exert a force.

Nevertheless, despite there being no forces, if there is a magnetic or electric field inside the region then there is energy there, as given above. Energy can be transferred to or from the region by increasing or decreasing the fields inside the region.
 

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