Can electricity flow through air w/out sparking?

You are talking about what I think of as capacitive coupling rather than electromagnetic radiation? Yes, that does happen, and is the main mechanism for fluorescent lamps and neon lamps to light up a few feet from a Tesla coil. Source and target are effectively plates of a capacitor, usually a non-ideal capacitor. The air (vacuum also works) is the dielectric.

This is normally not an efficient way to move power, although a few exceptions to this could be made as laboratory curiosities - and then optimistically that can transmit power efficiently over a distance maybe the length or the width of the lab, and then probably only to a constant impedance load, and with eficiency still easily exceeded by that of using wire.

But with even low efficiency of moving power this way, plenty of audio circuits run into problems with AC line power getting into them that way, and some amplifiers run into trouble with this coupling means transferring a bit of the output to the input.

A lot of audio circuits would get easier and a lot of shielding would not be needed if the dielectric constant of air was zero rather than close to 1. However, speed of an electromagnetic wave through a material is C divided by square root of product of permeability and dielectric constant of that material, so it appears to me that air having dielectric constant much below 1 is going to be hard to find!

- Don Klipstein ( snipped-for-privacy@misty.com)

Each time I see this thread title, I get more upset. Yes! Look up ionization chamber/

Bill

Without a unique definition for the word "electrcity," this discussion makes no sense.

In most books the word "electricity" means electrical energy. Or in other words it's 60Hz EM radiation being guided along a 2-wire transmission line.

Search google for keywords "KWh of electricity." Then search on "coulombs of electricity." The more common use by far is electricity=energy. Therefore a flow of electricity is *not* an electric current, and a flow of electricity is measured in watts, not amps.

When electrical energy flows across a circuit from a source to a load, it always flows in the region surrounding the conductors and not inside them. The flow is described by the cross product of the e-field and the b-field outside the wires. Inside the wires the e-field is insignificant, and since the small field is axial, it gives an energy-flow vector which is *inwards.* This makes perfect sense, because wires become warm only because electrical energy is flowing from the surrounding space and into the metal.

That's a flow of charge, not a flow of energy or "electricity."

Note that scientists have for the most part abandoned use of the word "electricity" to mean charge. Faraday and Maxwell may have used it, but since the early 1900s the textbooks have dropped it. They no longer mention "quantity of electricity" but instead call it "quantity of charge."

Well, it's a current density. So a more appropriate measure would be 1 microamp per square millimeter, or something. If the ion drift is a meter per second, then this implies that a microcoulomb worth of charged air can take the form of a cylinder 1M long and ~1mm in diameter

If 1uA/mm^2 were a typical value for non-corona, then we could silently transmit 100uA through a 1cm pipe, or 10mA through a

10cm pipe. Hmmm, sounds a bit large when compared to the current on the belt of a classroom VandeGraaff machine.

Nikola Tesla was putting vacuum bulbs on the top of small Tesla Coils. They produce a fan-shaped visible glowing beam several feet long. Today we would describe this as a pre-ionized path created by x-rays then lit up by a few milliamps of high-freq current. With x-rays involved, we can convert the air into a fluorescent lamp. Use it to light up your bedroom and also light up your internal organs at the same time. What fun!

:)

((((((((((((((((((((((( ( ( (o) ) ) ))))))))))))))))))))))) William J. Beaty Research Engineer snipped-for-privacy@chem.washington.edu UW Chem Dept, Bagley Hall RM74 snipped-for-privacy@eskimo.com Box 351700, Seattle, WA 98195-1700 ph425-222-5066 http//staff.washington.edu/wbeaty/

I'm talking about AM radio - and maybe I'm using terms so loosely that I am using them incorrectly..

--
A nation of sheep will beget a government of wolves. 
--Edward R. Murrow

I can believe that!

Bill

-- Ferme le Bush