What are your thoughts on this presentation on the concepts of electricity? / Electromagnetic Radiation / Forums

Forums

4hv.org :: Forums :: Electromagnetic Radiation

« Previous topic | Next topic »

What are your thoughts on this presentation on the concepts of electricity?

previous 1 2 3 next

Move Thread

LAN_403

Hazel1919

Fri Aug 03 2012, 10:40AM

Registered Member #1376 Joined: Wed Mar 05 2008, 08:31AM
Location:
Posts: 49

This should not be a matter of poking holes in a theory, but a way to gain better understanding of what is happening.

For example, I don't know if you read this, but I wondered about this quote from Steinmetz...

"Unfortunately, to large extent in dealing with dielectric fields the prehistoric conception of the electrostatic charge (electron) on the conductor still exists, and by its use destroys the analogy between the two components of the electric field, the magnetic and the dielectric, and makes the consideration of dielectric fields unnecessarily complicated... There is obviously no more sense in thinking of the capacity current as current which charges the conductor with a quantity of electricity, than there is of speaking of the inductance voltage as charging the conductor with a quantity of magnetism. But the latter conception, together with the notion of a quantity of magnetism, etc., has vanished since Faraday's representation of the magnetic field by lines of force."

I think terminology is different here, correct me if I am wrong please, but Dielectric lines of force as referred to are electric lines of force as considered today. The electric field is therefore composed of the circular magnetic flux lines and the dielectric flux lines which terminate on the "electrons" and "protons" the magnetic and dielectric being perpendicular everywhere they cross. The ratio between the two quantities is equal to the speed of light. That was Maxwell's discovery.

So if I read correctly, We don't say that the inductance voltage "charges" or gives a quantity of magnetism to a conductor, but we do say that, for capacity current, a capacitor is charged with a quantity of 'electricity', i.e. Dielectricity?

I foundd 1:03:30 - 1:11:00 of particular interest.

So when considering the space between a simple pair of wires in the picture below, like telegraph wires, we have an electromagnetic field like in the picture attached below. The telegraph wires would be going in and out of the screen so it's like a slice picture of the field.

The total amount of 'Dielectrification' i.e. the total number of dielectric flux lines between the conductors is denoted by psi Î¨ . Similarly the total 'Magnetization' in the system is denoted by phi Î¦ . The point at which the two components cross over is denoted by Q i.e. the total electrification of the system.

Therefore Î¨ x Î¦ = Q
Q / Î¦ = Î¨
Q / Î¨ = Î¦

So according to Steinmetz, electricity HAS to be the product of Î¨ and Î¦ which means a charged capacitor is not electricity.

Dr. Slack

Fri Aug 03 2012, 03:15PM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

Plasma wrote ...

So according to Steinmetz, electricity HAS to be the product of Î¨ and Î¦ which means a charged capacitor is not electricity.

Stop worrying about what "electricty" means. It's just a word. Like any ill-defined word, it can morph to mean power or charge if one uses it carelessly.

Start worrying about what the symbols in Maxwell's equations mean, what quantities they are measuring.

So yes, a charged capacitor is not electricity, it's a charged capacitor.

Hazel1919

Tue Aug 07 2012, 12:42PM

Registered Member #1376 Joined: Wed Mar 05 2008, 08:31AM
Location:
Posts: 49

Electricity, as defined by Steinmetz, is the product of Î¨ and Î¦.

Steve Conner

Tue Aug 07 2012, 12:52PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Well, I know Steinmetz's "electricity" as the "Poynting vector", the cross product of the E and H fields. It has units of watts per square meter and represents the flow of electrical power in a system.

A charged capacitor sitting on a table is static electricity. The Poynting vector is zero everywhere in and around it, no power is flowing and it is doing no work. However, in order to charge it up, power had to flow into it at some time.

Tetris

Tue Aug 07 2012, 08:59PM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

TL;DW, but looks interesting. Any presentation that has at least one true thing to teach me is good.

Hazel1919

Sat Aug 11 2012, 07:09PM

Registered Member #1376 Joined: Wed Mar 05 2008, 08:31AM
Location:
Posts: 49

I would like to just put this question out there: What is your definition of a volt?

Steve Conner

Sun Aug 12 2012, 09:09PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Some practical definitions:

Two-thirds of an AA battery.

An electric field such that when developed between the terminals of a voltmeter it reads 1 volt.

I believe the official definition is made in terms of a superconducting Josephson junction or something equally gee-whiz.

Mattski

Mon Aug 13 2012, 03:44AM

Registered Member #1792 Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527

The concept of voltage is that the voltage between two points specifies the difference in electrical potential energy which exists between those two points. If a charge moves between these two points a certain amount of energy is imparted to it.

It's just like if a ball rolls down a hill a certain amount of gravitational potential energy is imparted on the ball, and the amount of energy per mass is determined by the height difference* and the local gravitational strength.

Groups like NIST define Volt the unit in terms of something that can be quantified and measured, which is currently the gee-whiz Josephson junctions :) It used to be defined by standard battery cells.

*Making the common approximation that gravitational force is constant versus position near the surface of the Earth.

This is all basic physics, so the fact that you're asking suggests that you disagree with the accepted definition of the volt. Do you prefer an alternate definition because it provides better insight while not being inconsistent with the standard definition, or do you think think that the standard definition of the volt is fundamentally incorrect?

Hazel1919

Mon Aug 13 2012, 11:03AM

Registered Member #1376 Joined: Wed Mar 05 2008, 08:31AM
Location:
Posts: 49

Yes, that is very interesting. I have always considered a Volt to be a certain difference of potential.

I am very interested in the original definitions (aka as defined by coulomb, Faraday, Webber, plank etc) or, as it is put in the video, 'basic geometric proportionality'.

So Steinmetz says that the magnetic field and the 'dielectric' (as Faraday called it) field are the two factors of the electromagnetic field: Î¨ x Î¦ = Q. So, electricity has to be the product of these two components. These two quantities are the foundation for the definitions of the Volt, Amper, Joule, Watt, Ohm, Siemens etc...

For example, if you vary the total electric field, Q, with respect to time, in other words, in a given amount of time, T, the quantity of 'electricity' changes, that is defined as Work in Joules.

Q / T = J

Further, if you take the total magnetism and vary that with respect to time, either strengthening or weakening it, you have E or elector-motive force in volts. That is the definition of a volt. A volt is the rate at which magnetism is produced or consumed in an electrical system! I don't remember ever learning that, and yet these are the original discoveries made by the men who founded our modern world.

Î¦ / T = E

Similarly, if you take the total 'Dielectric' field and vary that with respect to time, i.e. produce or consume the electric field, you have I or Magnetomotive force in Amperes.

Î¨ / T = I

The definition of an amp.

Remembering that total electrification equals the total dielectrification x total magnetism, if we multiply each of these quantity's with respect to time we have power P in Watts

Î¨ x Î¦ = Q, we can say that (Î¨/T) x (Î¦/T) = Q / TÂ²

We can use this to define inductance, capacitance, conductance and impedance also by looking at their proportionality.

So if we have a magnetic field, Î¦, and current, I, associated with it in an electrical system, and take the proportionality of the two we have the magnetic inductance i.e. the definition of inductance in Henries. In other words, "inductance is the total magnetism compared to how much current was required to produce it".

Î¦ / I = L

As a practical example using generalized units that show the proportionality: If you can produce 100 units of magnetism for 1 unit of current as compared to 1 unit of magnetism for 1 unit of current, the 100 units of magnetism for the 1 unit of would have 100x the inductance of the other situation.

100Î¦ / 1I = 100L > 1Î¦ / 1L = 1L

So this serves to show the basic proportionality.

Equally, if you have a 'dielectric' field compared to the voltage associated with it we call that C or Dielectric capacitance in Farads. e.g. for every "quantity of Dielectric field, there has to be a certain amount of electromotive force that give rise to it".

I am much more familiar with the following definitions of impedance and conductance in the form of one of ohms laws. So looking from the Magnetomotive point of view, if we take the Ratio of the Electromotive force compared to the Magnetomotive force, we have impedance in Ohms.

Conversely, looking at things from the Electromotive point of view, if we take the Ratio of Magntomotive force compared to the Electromotive force we have the conductance.

E / I = R and I / E = Y or admittance, as it was called by Steinmetz and Heaviside, in Siemens.

So I thought that was very interesting, and we have Ohm to thank for defining these ratios!

Plasma,

Steve Conner

Mon Aug 13 2012, 11:57AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

This is all correct, just the terminology is outdated and the symbols are different to modern use.

wrote ...
A volt is the rate at which magnetism is produced or consumed in an electrical system!

Indeed this is a statement of Faraday's law of induction, which ended up as one of Maxwell's equations:

previous 1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob