Testing the TK Tar Baby

[TinselKoala]

A quick aside: Charge is conserved.

What is meant by such a statement? Well, we've heard the same thing about energy haven't we. Energy cannot be created or destroyed, only changed in form, yada yada yada. Believe it, or not. The Universe doesn't care one way or the other what you believe, it _acts_ like energy is conserved in every observation we've been able to make so far.

Charge... ditto. Charge is neither created nor destroyed; the unit negative charge on the electron and the exactly equal but opposite unit positive charge on the proton are deep and fundamental mysteries of nature and all we can do is to describe how they behave, using very careful observations indeed. Various nuclear processes that happen in extreme energy environments cause transformations, emissions and absorbtions and all the rest, emitting weird particles and stranger rays, but Charge, Momentum (angular and linear separately), Mass/Energy and almost always Parity are all conserved and must balance on both sides of whatever transformation occurs, always (at least so far and except for a rare interaction that does not conserve parity.)

And Charge is not Energy. It takes Energy (work) to move charges around against the forces produced by the interaction of that mysterious bubble of repulsive space: the Electric Field.

[TinselKoala]

Charge, motion, field: one thing. One.



After Kakua visited the emperor he disappeared and no one knew what became of him. He was the first Japanese to study Zen in China, but since he showed nothing of it, save one note, he is not remembered for having brought Zen into his country.
Kakua visited China and accepted the true teaching. He did not travel while he was there. Meditating constantly, he lived on a remote part of a mountain. Whenever people found him and asked him to preach he would say a few words and then move to another part of the mountain where he could be found less easily.
The emperor heard about Kakua when he returned to Japan and asked him to preach Zen for his edification and that of his subjects.
Kakua stood before the emperor in silence. He then produced a flute from the folds of his robe, and blew one short note. Bowing politely, he disappeared.

[TinselKoala]

Current, voltage, resistance: Ohm's Law.

V=IR

Ohm's Law isn't like a speed limit or the requirement to attend Mass on Sunday. It's not a Law in that proscriptive sense. Rather it is a set of circular _definitions_ that are interlocked inextricably like the physical quantities they represent.

In the math expression of Ohm's Law, Voltage is designated by V in Volts, current by I in Amperes (don't ask why, I dunno) and resistance in Ohms, named for... guess who. And Power, which is the Rate at which energy is expended or converted or dissipated, however you look at it, is measured in Watts, W.

OK, so Ohm's law is a simple algebraic expression that defines each of the three units (or four if you include Power) in terms of the others.
DOING THE MATH, we get a family of equations, all equivalent algebraic expressions of the same underlying definition.

V=IR.  Volts equals current times resistance (recalling the units of each).
I = V/R. Current in Amperes equals Voltage divided by the Resistance in Ohms.
R = V/I. The Resistance of a circuit in Ohms equals the Voltage divided by the Current in Amperes.

and further, since DC power is just P = V x I, voltage times current, we arrive at
P = I²R. Power in Watts equals the square of the current, multiplied by the resistance. (sorry, edited the usual typo here)

Now from our discussion of the Voltage Game it should be clear that whenever there is a Voltage present, and a place of lesser voltage connected to it by some traversable channel, charge will flow, until the pressure on both sides of the channel... the voltage... is equal.
And... now going even farther back to the introduction to the Hydraulic Analogy, the Rate of this flow will be proportional to the degree of constriction of the pipes and valves, for a given amount of head, or pressure...or voltage. Hence, we see that the Resistance defined in Ohm's Law is what keeps Current from becoming infinite, between two different voltages connected by a channel. (No resistance, the voltage difference equalizes instantly, hence infinite current. Infinite resistance means no channel, no current, and the voltage difference remains unchanging.) And all points in between are covered by Ohm's Law.

So what is resistance then, physically? Well, you can think of it as similar to having really narrow passages between the desks, in the Voltage Game's simulated metal lattice. The charges can't move through the lattice as easily as with wide corridors so, for a given voltage level, the current is reduced. The electric fields (the desire to not touch and lose the Benjamins) of the charges interact with the electric fields of the nonmoving lattice and so it takes more work to push them through at the same rate: if you raise the voltage you can raise the current, for a given resistance. And finally, moving the desks even closer together, or putting more of them  in the room, raises the resistance ,which lowers the current if the voltage isn't raised somehow.

So Voltage can be thought of as the "force" that pushes Current through Resistance.

And Current is the response of charges to a Voltage pushing them through a circuit's resistances.

And Resistance is that property of conductors and other circuit elements that impedes the flow of Current, hence requiring more Voltage to achieve the same Current as was obtained without the Resistance.

And Power is the RATE of the performance of the work done by the Voltage pushing the Current of charge through the Resistances of the total circuit and its materials.

V=IR, Ohm's Law. Voltage, current, resistance: One thing. One.



OK, thanks for your attention. I highly recommend that everyone simply memorize that V=IR equation. All the rest can be derived from that one simple statement of Ohm's Law. See you tomorrow, have a good evening and try, in some way if you can, to reduce the suffering of some sentient being somewhere.



Next: A return to the Hydraulic Analogy, and some simple circuit elements.

[TinselKoala]

Nobody could adjust the picture on a colour TV like me!  lol  The sweet spots.

What the carpenter didn't know was that Sen no Rikyu cheated. When the carpenter went to fetch his saw, Sen discerned the carpenter's mark and placed his own subtle one beside it.


Just as you, probably, knew about where the knobs should have been set before you started--- a baseline was established from which to measure and work, even something as simple and subtle as the position of a screwdriver slot wrt the corner of the room.

[markdansie]

Hi TK
I am enjoying your series on Ohms Law for dummies.
One thing that has been puzzling me for months. If you and the RA were to mate and produce off spring what sort of child would you have? Would the child be forever torn between the the separate universes you work from?
Pure speculation I know......but still I wonder.
I was in SA earlier this year on another wild goose chase, I forgot to see if RA would meet up. I had a competent physicist with me with two suit cases full of test equipment. Still kicking myself about that.


Kind Regards
Mark Dansie