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What? the OP said a 9V battery didn't spark. I did the test.

So now I think it's an energy thing. How many joules can you see? Of course there's a time component too. Does that make it a power thing?

George H.

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780, but the math part was way too easy. I did a lot worse english part...... you can probably tell from my posts.

George H.

I've read that a dark-adapted human eye can see a burst of around a hundred photons. You can certainly see a single alpha particle hit a phosphor, which isn't a very efficient transducer.

I've also seen the claim that cats can see single photons.

I can see a good green LED, in office light, from a couple feet away, at about 100 nA. That must be picowatts entering my eye. I'll have to try it in the dark.

John

He goes with the only thing he knows. :(

--
You can't have a sense of humor, if you have no sense!

A little "science fair" motor made from a coil of wire and paper clips easily proves that sparks can occur using an AAA.

** ---* *--- **

That's the coil soldered on each side to an "axle" of stiff bare copper wire. The "axle" sits in the U of unfolded papers clip at each end. The paper clips are screwed to a block of wood. A permanent magnet is positioned below the coil, and the battery is connected to each paper clip. Give it a push to get it going, and it spins nicely.

I've see the sparcs/arcs, but even if you don't see them, you can see the burn marks on the U pieces and the "axle" after it has run a while, so you know there had to be sparks. Darn thing works _because_ the "axle" bounces in the U ends, making and breaking the circuit - and causing the sparks.

Ed

OK

Not necessarily. This depends on the circuit parameters. If there is no inductance, there may be no voltage rise but you may still have an arc. However, inductance is not necessarily associated with the inertia and mass of the electrons- You appear to assume a mechanical relationship which may or may not be. Certainly the mass and inertia is involved in electron movement in the initiation of the arc- but this is a result of the field between the contacts, rather than the other way as you imply. I am interested in your reasoning because your mechanical/ hydraulic analogy, while useful to a point, may break down.

Zed is pretty well on target-although I question his 30 V lower limit on the basis of some arcs that can be drawn from 12 V batteries.

--
Don Kelly
dhky@shawcross.ca
remove the x to reply

Did you collect ANY of the debris flung outward by the spark target location?

If not, then you are too stupid to even know what proper experimental observation is, much less what performing it properly entails.

through an insulating material.

This places the source in question.

The onset of current flow in ANY circuit is an instantaneous catastrophic event that is some cases is VERY catastrophic. If it takes place through air, the event can be observed in many cases.

This is why many circuits fail at the initiation of power to the circuit, and also why "soft start" circuitry was designed and implemented.

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With eyes closed, I have seen what appears to be points of light, also in a completely dark room. I think it is a nervous thing similar to the occasional "ringing in the ears" phenomena that many if not most humans hear at times.

You can also watch a stock ticker scroll on TV, or the road pass under your bike, and then look at a matte surface (the sky) and see things continue to scroll as your brain re-trained itself to handle the scrolling "scenery" (or segment thereof for the stocks), it can be observed while it resets back to normal "screen refresh" mode. A weird phenomena, in my view.

We can probably see less than a 100 photon packet after many hours of darkness and acclamation to it.

That is why I have most of you shitheads pegged to a tee.

Bwuahahahahahahahha!

Being a motor, however, we deal with back EMFs, but yes, I have seen sparks on shorted standard cells (at the moment of the short).

"Don Kelly" wrte news:iNDsm.58579$ snipped-for-privacy@newsfe07.iad...

You are a typical slave of texstbooks. The field methods were developed for the electricity as an incompressible masless fluid. Poisson made the math for the two fluids and next Maxwell for the one. The both math are beautiful. Teachers use them to teach the field methods. But in all textbooks is mentioned that in metals are "free electrons" (electron gas) with mass and inertia. After schools all engineers work on electrons.

So "your mechanical/ hydraulic analogy, while useful to a point, may break down." is not correct in the two places:

1. In electronic industry is mechanical/gas analogy (not hydraulic).
2. "may brake down". No such possibility. It is fully usefull.

Here is the question "Why no math for the gas analogy"? Probably engineers prefer "trials and errors" method. S*

You're far worse than the slime, and it's a travesty that you take the name of the great FZ in vain.

You're an idiot.

You're an imbecile. So there!

What do you do?

John

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I have pretty intense phosphenes, basically a continuous light show in the dark.

It's fairly dramatic and has interesting patterns, but isn't a bother and doesn't seem to impair my night vision. I also get migraine auras, intense light shows that temporarily impair my vision (triggered by food allergies maybe?) which are visually fun; I get the aura once or twice a year maybe, but without the headache, which is unusual.

Swimmers, too. Has anybody figured them out?

I think that's common.

I've got to try the green LED thing and calculate the minimum preceptable CW power level. I wonder is that's more or less power than is audible?

John

It took me about two of his posts to filter him - now the only time I have to see his crap is when the trollfeeders come out to play. ;-)

They (the trollfeeders) apparently find it fun - I tried it a couple of times, but I got bored with it, because it doesn't seem to accomplish much. :-/

Cheers! Rich