What electricity really is

I purely by chance read something on quora digest that electricity isn't the flow of electrons but photons that are ejected from free electrons then re absorbed by another free electron this process makes them vibrate  and move forward a fraction of an inch. Now I know there was a discussion  about this on here a while back so what was the final conclussion. I know its a tough subject ide like to get my head round it of course its made harder because I can't understand the maths. 

  • Well it rather depends what you think electrons are - particles of known mass, known magnetic moment, known charge, and yet immeasurably small (though how small 'immeasurable' is keeps falling with better experiments, the diameter of an electron is is still one of those that is a 'less than' quantity)

    Like all objects with mass, when on the move, electrons also have a wavelength, (read up on Mr de Broglie if this is unfamiliar,)

    Photons are simply the smallest quanta of any given frequency of electromagnetic radiation. As such they have velocity, momentum, no mass and a wavelength related to the frequency, with the right  kit, a sort of modified cathode ray tube, a variations on the two slits experiment for demonstrating the wave nature of light, works just as well to demonstrate the wave nature of electrons as well.

    If you want to consider a static electric field to be a  representation of the chance of intercepting a DC photon then yes electons radiate those, in the sense they create a field. It may not be that useful as a concept.

    Then any other electron, or other charged thing, in that field (or probability of intercept) will be acted on by a force (quantized, but for DC infinitesimally so) and experience a force..

    Now please consider exaclty what stops you falling through your chair, when you and it are both mostly empty space. (between the electrons on the outer shells of the atoms  and the nucleus is nothing but the vast emptiness of 'solid'  matter - an atom is about 1/10 of a nanometer accross, while the nucleaus is a few times 10^-15 m - that is a lot of emptiness).

    Clearly  there is  repulsion between the electrons of the atoms of 'chair'  and those in the atoms of 'person', both charged particles in each others fields, and an exchange of forces  occurs - the same between a hammer and a nail too. If you want to think of this as photons, it is perfectly valid to think so. It is however one of the less useful models compared to fields.


  • Regardless of what electrons and other charged particles are (and are not), the phenomenon of electricity and how it transfers energy in a circuit or semiconductor is still not fully known.

    The fact we have to use the terms "electric field" and "magnetic field" as if they were some magical force is the clue to this. The action of gravity is no different, though.

    As Engineers, we don't always need to fully understand the science (although we need a good appreciation of it). What we do need to be able to do is understand the limitations of any models or concepts we use - that is, the boundaries between which the models continue to be predictable, and outside of which a result is not guaranteed.

  • Regardless of what electrons and other charged particles are (and are not), the phenomenon of electricity and how it transfers energy in a circuit or semiconductor is still not fully known.

    'known' is not however the same as 'understood', and it can be a bit of a philosophical point, for examples semiconductors are extremely well understood in the sense we can calculate, predict and then make devices that perform extremely close  to those theoretical predictions. 

    EM Fields may be a concept from the 1800s, but they are still doing very well in explaining the operation of the WiFi that links this computer to the network as I type, and the behaviour of the electrons and holes in the semiconductors within it.

    The big thing the normal education process tends to imply that there are fixed facts, and that what is printed  in the text books is in some way the last word,  and then folk often struggle later when some improved understanding emerges.

    Rather like 'Old MacDonald had a farm' where you have to sing back through all previous verses. any new model has to still explain  all the experimentally observed stuff covered by the previous model as well...  the previous is not 'wrong' in a ten commandments sort of way,  more 'incomplete', or 'not the best model for this sort of problem'


  • Agreed, I think we are making the same point, in that we understand (within certain parameters) the observations we will make in given circumstances. But we must accept there are boundaries to that understanding.

    For all we know, whenever we drive energy through an electrical circuit, we might be causing quantum destruction or quantum transformation events at a remote point in this universe (or another parallel one) ... we just may not have observed it yet! (I'm not, by the way, actually proposing this is the case, but using it as a thought-experiment example to illustrate bounds of knowledge.)

  • A couple of questions on that theory:

    • Where do the electrons get enough energy to release a photon?  Imagine a copper wire sitting in a bath of liquid nitrogen, connected to a supply of <1 volt.  There's very little energy to excite the electrons, so that they can then release photons.
    • How do the electrons know which way to emit the photons?  If it's random, then there will be no overall current.
  • The photon only exists as a particle after its effect has been detected- by nudging another charge. Until then it is omnipresent with a probability of detection at any given point that is the 'field strength' due to that charge.

    My wife is similar, I have no idea where she is, until the probability of detection waveform collapses, and then I do. This too is accomplished by photon exchange, through this is detecting secondary photon scattering rather than generation (as neither of us glow at visible wavelengths n the dark), and at closer ranges a (sometimes quite terse but then more energetic * ) exchange of phonons occurs as well.

    As you approach DC == electrostatics, the energy per photon approaches zero, and at the same time the wavelength approaches infinity (there are no periodic field reversals with distance == DC.) so launching an infinite no  of photons  of zero energy and infinite wavelength takes no energy. (zeros cause problems) Better to talk about semi-infinite DC - where the charge is turned on at time zero but then never moves or reverses polarity. The only energy put in is that to manoeuvre the charge into its static  position at T0.


    * She is part Brazilian....

  • At the heart of every photon is a magnon of spinning area of magnoflux inertia. If this massless magnetic momentum field is attracted forward at right angles by a voltage we get electric power. If the voltage is not at right angles we get a Cosine reduction in power and start producing VAR's or quantum photons. 

  • heart of every photon is a magnon of spinning area of magnoflux inertia.

    Not in any model I recognize there is not. Magnons are simply the exchange particles for magnetism in the form of spin waves and experience no forces from static electric fields - the things that do are charged, not magnetic.


  • Mike

    Please do the locked induction motor experiment yourself and let us all know the result.

    Thank you.

  • I assume you are referring to this experiment where as one would expect from the series L-R and voltage source from the armature model, as you stall the motor the resistance term representing the mechanical load falls to zero and the current rises and becomes more imaginary? 

    The experiment would benefit from a 'scope showing the phase offset between supply voltage, primary current and the current in the shunt windings - the whole point of a shaded pole motor is that the magnetic flux in the core is retarded in the vicinity of the shunts, to give the effect of a rotating magnetic field from a single phase excitation - which after all is what pulls the squirrel cage in a particular direction.

    Note also that the current in the shunt windings would be noticeably higher without the clamp ammeter - in this case the one turn around a cm2 or so of laminated iron in the meter "jaws" is not totally negligible in comparison to the area of iron enclosed from the  motor core.

    I agree that magnetism (and complex nos for that matter) is appalling taught to most electricians, and that leads to a lot of misunderstanding and confusion, not helped by some incorrect drawings in text books.

    Where I differ, strongly, is that  I see no need to add further to the confusion by adding a new pseudo-particle. And  as it happens the name magnon is already used for something else,.


    A schematic of a shaded pole motor - which is what  I think that is  in the video - the sense of rotation is from the open part of the pole towards the side which is 'shaded' by the near-short circuit winding (or windings) - though washing machine pumps are usually a variant with one primary winding and the iron work forming a horse-shoe with the rotor completing the magnetic flux between the poles of it - see photo - cheers Wikipedia, .  The time delay between main and shaded pole areas is nothing like 90 degrees though, (I think 20-45 degrees perhaps) and this poor sense of direction translates into a  weak starting torque... as you note it is almost a transformer, albeit one where most of the magnetic flux from the primary coil misses the shorted secondary completely (*).

    As induction motors go shaded pole machines are pretty poor , so tend to be seen in low power situations where torque is not critical - capacitor start and two real windings is a far better way to get a spinning field on single phase if you need something with a decent pull.


      (*). A similar game is played with microwave oven transformers where the core is shunted, so quite a lot of the magnetic field linking the primary and the heater winding  is steered round so that it misses out on the HT winding - giving a performance rather like an ideal transformer with a current limiting extra inductor in series, which limits the peak HT current in the magnetron - a crude "almost constant current" drive.