Testing the TK Tar Baby

[polln8r]

TK,

A supplement to the a.s VR18, to help illustrate the concept in your video in case it wasn't clear.
http://www.youtube.com/watch?v=iZhEcRrMA-M

MIB! That's preposterous! (Everybody knows they really wear grey).

polln8r

[TinselKoala]

Great! You should post that as a video response, I'm sure I'll approve it instantly!

One of my all time favorite characters.


Meanwhile... it seems we've attracted some more attention from the Southern Hemisphere. Some one down under seems fascinated by the brilliance of the Light:

[TinselKoala]

Flawed concepts of fundamentals will prevent the interested student from being able to understand further ideas that depend on a proper underpinning. To get the more complicated ideas, like "what is voltage" or "what is current" , one absolutely must have a grasp of some very basic concepts, and if these concepts are misunderstood... or even DENIED.... then further understanding of even seemingly simple things like relative voltages and how current flows and in which direction will be severely impeded. Please bear with me while I review some of these vital fundamental concepts.

Electric charge is fundamental, and is a conserved quantity. It is the interaction between charges of opposite polarity, and the motion of these charges, that comprise quantum electrodynamics (QED) in its entirety. QED is the "standard model" of electricity, electronics, electromagnetism, electrostatics, ion chemistry, molecular bonding... all of that is covered by QED and is understood well enough under that model so that we can calculate.... CALCULATE... based on a few fundamental quantities, the behaviour of any electrical circuit (and much more). The basic relationships amongst charge, motion, and force are contained in what is perhaps the most "sacred" and elegant set of equations in all of mathematical physics: Maxwell's Equations (ME). These equations take as input charge and motion (relative direction and magnitude) and return forces, directions and rates. Using ME and the further math that is derived from them, like Ohm's Law and KCLs, we are able to PREDICT with incredible accuracy the behaviour of circuits, devices and systems of these things. That is why circuit simulators actually work accurately: they are based on QED, which describes Charge, Motion, and Force.

Notice that ME don't talk about electrons at all. Charge, Q, is independent of its carrier in its relationships described by ME. Physicists have also been able to determine through an elegant (and huge) set of experiments that Charge is Quantized, that is, it comes in little discrete packets that have a smallest size and every Unit Charge is the same as every other. And they come in two flavors, Positive and Negative, and due to an accident of definition (thanks to Ben Franklin for a hundred years of confusion)  it happens that it is the electron, a particle, that carries the Negative Unit Charge. And it also turns out that the Unit Charge is inseparable from the electron; take it away somehow and you no longer have an electron at all, but some other particles from the PZ (particle zoo) and some energy. (The standard model of particle physics (PP) is properly called _The_ Standard Model with capital initials.)

So ME describe the motions and interactions and forces involved in MOVING CHARGES and how they effect each other. Charge is conserved; it takes energy to move things against opposing forces... but the charge is not the energy.

Now.... how do these Unit Charges happen to move, if they are attached to physical things like electrons and atoms that exist in solids like copper metal?

Well, it turns out that METALS, due to the structure of the electron shells around the individual atoms... have a lot of so-called "free electrons" that can be thought of as a kind of electron "gas" that is free to move around inside the metal's lattice formed by its atoms. These electrons are charged, each carrying its own little Unit Charge, and although the entire chunk of copper is "neutral" or balanced wrt P and N charges, the negatively charged electrons in the "conduction band"-- that electron gas-- are free to be pushed around however the forces applied make them go. In a copper wire, for example, it's like a bunch of little mutually repulsive pingpong balls in a tube, just big enough so the balls are free to move along the tube but can't push past one another. The balls are the electrons, the charges are what makes them repel each other.

So... if you push one of the balls in one end of the tube, this "wave" of mutual repulsion travels down the tube, as one ppball pushes the next one in line, never touching but transmitting the push through the mutual repulsion of the Unit Charges that are "stuck" to each electron. The electrons themselves need not move either far nor fast !! The repulsion of the charges causes the Last Electron at the far end of the tube to get pushed OUT at practically the same instant as you are pushing your First Electron IN to the tube at your end, even though you've only pushed yours in a tiny bit. The FORCE you use to push in is transmitted by the charge repulsion all the way down the line to the far end and thence to whatever that electron is going to push against.

All of this and much more is contained in precise mathematical relationships described in ME. They can be calculated, and give values that agree with experiment to an amazing degree of precision and accuracy. THIS is what is meant by a MODEL, in the physics and math sense. It agrees with observation, it makes predictions that can be checked by experiment, and most importantly it contains a means... mathematical relationships.... to quantify those predictions precisely and accurately. Models are accepted, to the degree with which they conform to experiment. When experiments and measurements become so precise that they reveal that the current model in use is not complete, then PERHAPS someone can come up with a new, better model... but that model has to be both CONSISTENT with what is previously known and also make BETTER, more precise or accurate or additional predictions of the behavior of experiments. That's what is meant by a MODEL, and that's what is needed for a better one to replace an old one: it really DOES have to be better, and it really DOES have to make numerically calculatable predictions that not only describe ALL previous behaviour that the old model did, quantitatively, but also must do its new thing too.

Enough for now. Thank you for your attention, and please think about Charge. Charge is fundamental and conserved; voltage, current, induction, capacitance, and all the rest emerge from the interactions of Unit Charges with one another.

Next: the Hydraulic Analogy.

[TinselKoala]

The Hydraulic Analogy.

Nan-in, a Japanese master during the Meiji era (1868-1912), received a university professor who came to inquire about Zen.
Nan-in served tea. He poured his visitor's cup full, and then kept on pouring.
The professor watched the overflow until he no longer could restrain himself. "It is overfull. No more will go in!"
"Like this cup," Nan-in said, "you are full of your own opinions and speculations. How can I show you Zen unless you first empty your cup?"

[TinselKoala]

OK, stand up and stretch, take three deep breaths and put on your bathing caps..... for The Hydraulic Analogy.

Electrical current, voltage and all that stuff is really esoteric, you can't really see them or, usually, feel them; they are just parts of some weird nonintuitive arbitrary description that some boffins came up with, who never go outdoors to water the garden at all, and might as well be totally imaginary. Right?

But everyone has some basic experience with garden hoses, buckets and barrels of water, waterfalls and calm lakes, elevated water tanks that use gravity to provide pressure at your hose, ocean waves, water pressure at the ocean depths, evaporation, condensation .....

And it just happens that the flow of Charge in electrical circuits can be described -- imperfectly but often adequately -- by the so-called Hydraulic Analogy (HA), where circuit components are modelled by things like tanks and reservoirs, hoses and pipes, pistons and cylinders, water balloons and waterwheels and so on, and the Charge is modelled by the water itself. And of course the Energy comes from whatever is pushing the water through the pipes: an elevated head (gravity or springyness) or an active pump of some kind converting outside energy into the "push" of the water.

It can be very instructive to analyze simple circuits and component combinations using the Hydraulic Analogy, both to understand how it conforms, and also to see just where it breaks down in analyzing circuit behavior. I still haven't figured out how to analogize inductive effects across space in the HA, for example, although the simple behavior of an isolated inductor is an easy fit to the HA.

OK, so this is just a teaser. Some electrical/electronic components and their HA analogues:

Water = negative charge, carried by electrons.
Pipes = wires.
Pockets of Air in the pipes = positive charge, the absence of negative charge where it normally should be.
Tanks, reservoirs = batteries, capacitors.
Rubber Water Balloons = simple inductors.
Active external pumps = power supplies, the ion chemistry in batteries.
Valves = switches, transistors, diodes, vacuum tubes.
Partial blockages and constrictions in the plumbing = resistors.

There is more to the HA yet, like waves and their characteristics. But we'll save that for later; life intrudes upon us all and so we shall dismiss for now and resume later this afternoon. Thanks again and have a nice lunch.... thinking about the HA while you suck your Pepsi up a straw or pour your tea into a (hopefully not already overfull) teacup.