I don't want to restart a old argument but I fail to see the reluctance of some to fact of all electrical energy (DC to ~) in classical theory moves by fields (or photons in quantum theory) I understand some were taught electron flow with pipes of water "analogies" in school and it can be a shock at first but one just has to live with the initial confusion and 'get over it'.

 

Electricity in wire is electrons, the are the charge carriers. It can be other forms in other media, but in a metallic lattice the mechanism is well understood. Look up the definition of an amp, for example. It to is very clear cut when talking current in a wire.

 

Electricity in wire is electrons, the are the charge carriers. It can be other forms in other media, but in a metallic lattice the mechanism is well understood. Look up the definition of an amp, for example. It to is very clear cut when talking current in a wire.

And, so ...

... continue the argument.

Are you stating this because you think anyone in this debate doubts this? For the record, I will say that of course we know this.

Unfortunately this is an isolated fact that does not explain how power/energy is transported. The idea of the electrons carrying energy on their own, without regards to fields, is too simplistic an idea. Specifically, the same number of electrons flow in to the load as flow out, so each electron must give up potential energy for your viewpoint to make sense. That's fine, and even though you have not explained this, it provides a reasonable viewpoint. However, the idea of potential energy goes hand in hand with electric field. How did that field get there, if not by electromagnetic effects?

Did you look at the reference given by nsaspook? Hopefully you did. Go back and look at Fig. 4 of this document. Do you see how the DC case has one wire with positive charge and the other wire with negative charge? A DC description does not tell you how that happened. You keep talking about charge, and yet you never mentioned this capacitive charging? Why did you ignore it and not tell us about it? That happened as a result of electromagnetic interactions (transients) that charged up the effective capacitor created by the circuit. In the end, the DC case allows you to keep this viewpoint because energy is stored in the fields. The source puts energy into the field at one end and the load takes energy away at the other end, and DC means the process is balanced. There is no conflict of propagation time because the underlying assumption is that the system was given a relatively long time to charge up. Ultimately, the energy transfer is coupled through fields and you can't arbitrarily divorce electromagnetics from what you call electricity.

 

Sorry, can not help myself. Hit my knee with a hammer, I jerk.

 

We need to separate matter from energy in any talk about "electricity".

Understanding Electricity and Circuits : What the Text Books Don't ...

As Arnold Sommerfeld (1952) has pointed out, metals are good conductors of current but nonconductors
of energy. Metals conduct current but space conducts energy and the best conductor of
electromagnetic energy is the vacuum!

 

Thank you all for offering a wonderful insight into the topic.... Wow... The spectrum of discussions from waves to quantum mechanics was really interesting.... I'll try to post what I could understand from this discussion....

The second post mentioned about travelling waves....!! I saw a simulation of Transverse Wave on Wiki.... And I think I am trying to get a feel of the situation as follows based on the description of transverse waves....

Lets assume just one rotation of the Generator (alternator)... 360 Degrees...

In a typical 50Hz System, the generator would complete one rotation in 20ms.... Lets assume that the Load (A resistor, for instance) is 300 meters away from the terminals of the Alternator.... so that it would take 300/300,000,000 = 1us for the first travelling 'node' of the wave to reach the resistor terminal....

The Generator is initially at Zero Position.... This corresponds to the Zero Crossing (node) of the wave....

Just as the generator begins to rotate, in the first one micro seconds time, the generator would have rotated by one thousandth of 18 Degrees... And in the process, the first node would have rapidly travelled to the load....

As the generator continues to rotate further, the node would keep travelling thru the load allowing the other parts of the wave to come thru.... After about 5ms, the generator would have reached the first quadrature position which corresponds to the first peak.... In that time, the leading node would have already travelled 1500 kms past the load....!!!

In 10ms the generator would have rotated by 180 Degrees and the second zero crossing (node) would be well on its way to the load... In the third quadrature of the generator's rotation, the first trough would be well on its way to the load and finally when the generator has rotated by 360 Deg., the last node would be moving towards the load....!! By this time, the first node would be 6000 Kms away....!!!!

I donno, if the above understanding is right or wrong or 'not even wrong'.... But that's how I could visualize the explaination of travelling wave....

 

This site has an excellent introduction to waves with many animations and slow motion video.

http://www.acoustics.salford.ac.uk/feschools/waves/contents.htm

 

To the OP.

I caution you to use care with mechanical Wave models to understand electrical energy. They appear similar at first glance during interactions with matter but the actual properties of a EM wave are very different.

http://www.aplusphysics.com/courses/regents/waves/regents_wave_characteristics.html

Circularly polarized electromagnetic wave.

http://en.wikipedia.org/wiki/File:C..._Right.Handed.Animation.305x190.255Colors.gif
http://en.wikipedia.org/wiki/File:Rising_circular.gif

 

They appear similar at first glance during interactions with matter but the actual properties of a EM wave are very different.

That's an interesting claim.

Are you perhaps suggesting that they obey not the wave equation, but some different one?

The site I referred is the best teaching site for waves I know. The first page I linked to is an index which includes 'Radio and TV'

Are these not electromagnetic?

 

'...When we speak of electricity, we think of current flowing through the conductors from generator to load. This approach is valid because the physical dimensions of the power system are large compared with the wavelength of the currents and voltages; for 50-Hz signals, the wavelength is 6000 Km. This enables us to apply Kirchhoff’s voltage and current laws and use lumped elements in our modelling of the power system. In fact, the transportation of the electrical energy is done by the electromagnetic fields that surround the conductors and the direction of the energy flow is given by the Poynting vector.'

VAN DER SLUIS, L. (2002) Basic Concepts and Simple Switching Transients. (2002) Transients in Power Systems. John Wiley & Sons Ltd. pp. 1-2​

 

the wavelength is 6000 Km.

Only in free space or something like air.

Suppose your copper conductor had a thick silver sheath, insulated from the copper. What would then be the wavelength?

 

That's an interesting claim.

Are you perhaps suggesting that they obey not the wave equation, but some different one?

The site I referred is the best teaching site for waves I know. The first page I linked to is an index which includes 'Radio and TV'

Are these not electromagnetic?

The comment was just about properties of mechanical waves described by most of the links on that page. Mechanical waves require a physical medium that can store energy, electromagnetic waves do not.
Waves & Oscillations In This Lecture… Mechanical Waves ...

An electromagnetic wave consists of two waves that are oscillations of the electric and magnetic fields.
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/maxeq.html#c3

 

Only in free space or something like air.

Suppose your copper conductor had a thick silver sheath, insulated from the copper. What would then be the wavelength?

If you mean like a coax cable it would depend on the dielectric between the conductors.

 

Hello,

In a coax cable the dielectrum gives a "velocity factor"
http://en.wikipedia.org/wiki/Velocity_factor

Bertus

 

@spook

You claimed, rather loudly, that the properties of mechanical waves are very different from those of EM waves.

Very different, especially for the introductory stuff the OP was seeking?

At elementary level.,they both exhibit interference, diffraction, refraction, reflection, beats, critical angle, doppler effect, huygens principle, standing waves and more.

At an intermediate level, they both follow the same mathematical equations, including damping, resistance, capacitance, inductance,.

At an advanced level we can introduce dispersion and complex exponential solutions, which is what is required to understand what Steve is talking about.
You also need this to understand the relationship to conductivity and what happens in a silver sheath, where there is no substantial external field or perhaps the example below.

How is power transferred through liquid conductors where the liquid ions interact with the supply? Here there is no external field effect. All the action takes place within the liquid.

 

@spook

You claimed, rather loudly, that the properties of mechanical waves are very different from those of EM waves.

Very different, especially for the introductory stuff the OP was seeking?


How is power transferred through liquid conductors where the liquid ions interact with the supply? Here there is no external field effect. All the action takes place within the liquid.

At the level the OP was seeking they are very different in the way that "ENERGY" is transferred in a electromagnetic wave down a power transmission line. The wave function for a mechanical plane wave is the same the fields of an EM wave but one describes mass and the other describes field energy.

 

Travelling waves, mechanical or EM transport energy.

Neither transport mass.

Incidentally the potential energy storage mechanism in some mechanical wave action is primarily independent of mass, but actually electrostatic in nature.

 

Travelling waves, mechanical or EM transport energy.

Neither transport mass.

Incidentally the potential energy storage mechanism in some mechanical wave action is primarily independent of mass, but actually electrostatic in nature.

My bad, should have said the medium of energy transport is mass in mechanical waves as the matter only moves a small amount unless the displacement from large amplitudes causes nonlinear effects.

My reason for saying what I did is that I've seen endless discussions about mechanical methods of electrical energy transfer in wires involving electron group velocity waves, electron compression , marbles or water in pipes and many other methods based on the movement of mass in a loop somehow in a simple DC circuit.

How is power transferred through liquid conductors where the liquid ions interact with the supply? Here there is no external field effect. All the action takes place within the liquid.

???
http://www.technologyreview.com/blog/techspecs/26041/
http://www.youtube.com/watch?v=9tIZUhu21sQ

 

My reason for saying what I did is that I've seen endless discussions about mechanical methods of electrical energy transfer in wires involving electron group velocity waves, electron compression , marbles or water in pipes and many other methods based on the movement of mass in a loop somehow in a simple DC circuit.

I am not disputing that there is an EM field associated with wiring.

However I am delving more deeply into the question of how does it get there?

Conventional wisdom has the current distribution evenly across the conductor cross section for frequencies of the order of 100 Hz.

A generator or mains supply does not provide an EM field at its terminals it provides voltage and or current. These come first.

 

I am not disputing that there is an EM field associated with wiring.

However I am delving more deeply into the question of how does it get there?

Conventional wisdom has the current distribution evenly across the conductor cross section for frequencies of the order of 100 Hz.

A generator or mains supply does not provide an EM field at its terminals it provides voltage and or current. These come first.

http://en.wikipedia.org/wiki/Litz_wire

At 60 Hz, the skin depth of a copper wire is about 1⁄3 inches (8.5 mm).

You won't see something this big in your house but at work we use a huge about of power so some of the larger buss bars are hollow to reduce cost due to skin effect.

Conventional wisdom is worth about the same as a bucket of spit.



Fin.