Is there a relationship between magnetism and energy (electrical)?

  1. As many people know, you can use electrical energy to create magnetism (electromagnets) and you can use permanent magnets to create electrical energy through induction (generators, the rotor inducing the stator). So what is the relationship here? Magnetism is not a form of energy or an energy carrier (of potential energy) from my understanding, so what gives? Where can I start in understanding this relationship? (is there a website or videos to help further assess this?)

    Sorry I'm just confused.
  2. jcsd
  3. Physics_UG

    Physics_UG 289
    Gold Member

    yes, it is called Faraday's Law
  4. Nice, thanks Physics_UG for the straightforward answer!

    I will have an interesting read this weekend about electrodynamics and so fourth.'s_equations

    I guess the only question that I have left is how does an electrical physicist know when a device he creates that converts magnetism (gauss) to electrical energy and vice versa, how would he know if such devices are efficient? I know that there are a lot of variables to consider such as windings (the type, how many layers, at what angle, what materials etc.) the types of resistance that would be found in the devices, how far the electric field would radiate, the type of current used and produced (ac/dc) etc. If there is more than one method of knowing this conversion is that method considered the most efficient to be the standard or would the standard be derived from theoretical mathematical process? (such as the more direct conversion of chemical and electrical energy because that deals with the same components of electrons from what I understand)
    Last edited: Aug 30, 2014
  5. This is what I read from another post [which deals with internal resistance from a electrical-mechanical energy conversion] which would suggest that such a formula would more or so be derived from empirical results rather than formulating a purely mathematical construct (makes sense due to the nature of mechanical energy)

    This is what was stated;

    "Suppose the height of initial release of the mass minus the height of detachment is h. Then if the mass falls freely (without flywheel), the total kinetic energy of the mass is mgh = (1/2)mv2. But in the case where it is attached to the flywheel, its final velocity at point of detachment is v1. So its energy at release is now (1/2)mv12. So the missing energy is (1/2)m[v2 - v12]. This was all transferred to the flywheel.

    If the flywheel were frictionless and the generator perfect, all the flywheel energy would be converted to electric power. All inertial energy remaining in the flywheel after release of the mass would also be converted to electric power. To maximize the total electric energy, the objective then is to make the final velocity of the mass v1 as small as possible. If the flywheel were massive and v1 were small, then the electrical energy would be nearly mgh. If mgh were expressed in joules, then mgh/3600 would be the energy in watt-hours, or in volt amp hours. "

    So I would suppose that the relationship of magnetism and electricity isn't direct, in the sense that the factors that I listed in my post from above would deal with imperfections and internal resistance which would differ from the conversions of electricity-heat or electricity-chemical because these ones are more direct.
    Last edited: Aug 30, 2014
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