Energy

[BloodyHeretic]

When you turn the sink on it is slow moving. This is Voltage. If it is moving slow, the voltage is low. If it is running fast, the voltage is high.

How hot is the water? This is the Amperage. If the water is cold, there is hardly any amperage. But if the water is hot, then the amps are high. If the water is boiling then the amperage could hurt or kill you.

I don't understand . Wouldn't the flow speed of the water be analogous to current?

Hardly, electricity travels at a constant speed in a circuit, changing the voltage or resistance does not change speed, merely the charge in the circuit. Current measured in amps is charge per second, so maybe it'd be best to say the current is like the litres/second coming out of the tap.

[Darwinian]

@Dar- exactly what do you feel happens at maximum entropy within this closed system then? Would time still be in effect as energy has stopped flowing? Without causality what would happen in the closed system?

Firstly, I'm not even sure that it is possible for maximum entropy to be reached. The trouble is that it just might be that in an ever expanding universe the point of maximum entropy accelerates faster that the universe can gain entropy.

But anyway, there will come a time when all the energy in the universe is so evenly distributed that it becomes almost indistinguishable from the pre-inflationary universe and just perhaps, given enough time, the whole system will undergo another 'big bang' and off we go again.

The only fly in the ointment of this theory is gravity. In the pre-inflationary state, gravity is still an important force and so entropy will be very low, however, in the heat death scenario, gravity plays no real part at all and everything is in thermal equilibrium so perhaps the universe will stay in a frozen and motionless state for eternity, not that eternity will have any meaning as if nothing ever happens then time has no meaning either.

Personally I think the branes will collide again at some point, as they have been doing for an eternity and the whole think will start again.

[reverendjeremiah]

When you turn the sink on it is slow moving. This is Voltage. If it is moving slow, the voltage is low. If it is running fast, the voltage is high.

How hot is the water? This is the Amperage. If the water is cold, there is hardly any amperage. But if the water is hot, then the amps are high. If the water is boiling then the amperage could hurt or kill you.

I don't understand . Wouldn't the flow speed of the water be analogous to current?

Keep in mind that this is merely a quick example of electricity. Power in electrons is obviously much more detailed. I teach my apprentices this so that when they start off they can have a good visual picture to compare to in their heads.

Voltage is very much a "pressure, or to be precise; "Electromotive force".

Amperage runs through resistance. In reality the more amperage (load) on the circuit the actual, physical heat that radiates from the circuit itself.

So no..this example is an accurate, yet simple analogy.

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When you turn the sink on it is slow moving. This is Voltage. If it is moving slow, the voltage is low. If it is running fast, the voltage is high.

How hot is the water? This is the Amperage. If the water is cold, there is hardly any amperage. But if the water is hot, then the amps are high. If the water is boiling then the amperage could hurt or kill you.

I don't understand . Wouldn't the flow speed of the water be analogous to current?

Hardly, electricity travels at a constant speed in a circuit, changing the voltage or resistance does not change speed, merely the charge in the circuit. Current measured in amps is charge per second, so maybe it'd be best to say the current is like the litres/second coming out of the tap.

Ony if you are dealing with DC. The corkscrew sine wave of AC flows between its maximum voltage, to zero, to its NEGATIVE maximum voltage at any given time frame snap shot.

[BloodyHeretic]

When you turn the sink on it is slow moving. This is Voltage. If it is moving slow, the voltage is low. If it is running fast, the voltage is high.

How hot is the water? This is the Amperage. If the water is cold, there is hardly any amperage. But if the water is hot, then the amps are high. If the water is boiling then the amperage could hurt or kill you.

I don't understand . Wouldn't the flow speed of the water be analogous to current?

Hardly, electricity travels at a constant speed in a circuit, changing the voltage or resistance does not change speed, merely the charge in the circuit. Current measured in amps is charge per second, so maybe it'd be best to say the current is like the litres/second coming out of the tap.

Ony if you are dealing with DC. The corkscrew sine wave of AC flows between its maximum voltage, to zero, to its NEGATIVE maximum voltage at any given time frame snap shot.
[/quote]

Yes of course you're right with regards to AC, but what plumbing system works on the basis of the water flowing opposite directions every hundredth of a second? A particularly tricky phenomenon to find an analogy for, at least from the realms of water works.

[Autumnlicious]

Never liked the water analogy anyways. Much better to read up on potential theory and basic E/M.

[Cinjin]

@ Rev ... I've never heard the water analogy before. It's not perfect, but it works nicely for what you're using it for and I may use just use it myself.
Nice one.

@tack ... good question to Dar.

[lilphil1989]

Hardly, electricity travels at a constant speed in a circuit, changing the voltage or resistance does not change speed, merely the charge in the circuit.

It depends what you're talking about the speed of. The speed of an electrical signal in a conductor might be fairly independent of current, but I was thinking in terms of the average bulk velocity of electrons, which is directly proportional to the current (with the constant of proportionality being the conduction electron density).

I suppose how you think of it depends on what you're interested in. The Rev as an electrician cares about the macroscopic behaviour of circuits, I as a physicist think in terms of the microscopics.

Amperage runs through resistance. In reality the more amperage (load) on the circuit the actual, physical heat that radiates from the circuit itself.

So no..this example is an accurate, yet simple analogy.

Oh, the heat of the water is an analogy for Ohmic dissipation. Now I understand!

[reverendjeremiah]

Yes of course you're right with regards to AC, but what plumbing system works on the basis of the water flowing opposite directions every hundredth of a second? A particularly tricky phenomenon to find an analogy for, at least from the realms of water works.

Oh yeah, I agree. It took me a while to find an anolgy for it..

..now lets keep in mind that these analogies are meant for beginners. People just starting off and having a hard time understanding electromotive force and all of its beautiful and deadly applications....

I use this type of analogy to explain forward and back flow on alternating current.

The screw. I pick up a screw and say. Lets put an imaginary border long ways down the screw. the top part of the screw is the positive feed. The bottom half of the screw is negative feed. The screw spins in one direction, but every time a portion of the screw spins it has the potential to be negative or positive depending on its phase at the chosen frame. So in this case, the screw isnt really going in any specifice direction, but is merely a potential to move through the path of least resistance. The actual electron particles, like the threads of a screw, hang on the outer edge of the circuit. In fact this rings very true when we consider that "electrical power" is the "bumping" of valence electrons of whatever element used as its conductor. Valence being the outer shell of electrons of the atom. This also leads up to me explaining what Hysteresis is

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

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

Thats when I pull out a copper pipe and and say that the actual copper is where the electrons follow along the wire, and that the outer barier of the wire/circuit is the path of least resistance in and of itself. The electrons tend to avoid the core of its medium. This is why the wires become brittle compared to the load X load time X current draw. Aluminum wires suffer HORRIBLY from hysteresis loss. Most importan circuitry are made with gold or silver wire. Silver being the best conductor known to man (because of its generous valence), but being difficult to work with because of its high (higher than copper) oxidation/tarnish rate.

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Never liked the water analogy anyways. Much better to read up on potential theory and basic E/M.

Agreed. But if you have a dumbass first year apprentice, then you have to give him pictures to help

You know...like a picture book for elementary students..hand him some crayons and hope he gets the concept

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@ Rev ... I've never heard the water analogy before. It's not perfect, but it works nicely for what you're using it for and I may use just use it myself.
Nice one.

Its not perfect. Its a primer to help beginers get into the train of thought...to get the basic concept of it beyond abstract numbers