why does a car battery spark

I saw Mr. Wizard do that once. ;-)

Many many years ago, in "Ripley's Believe it or Not" or some equivalent publication, there was a story that claimed that a boxcar full of steel wool was set on fire by snow.

The snow got into the cracks between the car's timbers and started oxidizing the steel wool, causing it to heat, igniting the whole batch.

But I haven't been able to verify or refute this - I read about it about a half-century ago.

Cheers! Rich

I can't name names, but apparently everybody here except the two or three that are maintaining that it won't.

Thanks, Rich

I've heard that those are "sintillations" cosmic rays going through your vitreous humour, releasing photons when they're intercepted by your eye molecules.

Or they could be your retina responding to the cosmic rays themselves.

Howcome you guys don't snip?

Cheers! Rich

When I was in South Korea, a couple of friends and I used to take the train here and there. These trains didn't have a caboose, so you could go to the tail end of the last car, sit on the floor with our feet dangling over the tracks, and watch the scenery recede.

When the train stops, everything in the world starts coming right at you! It's way cool, especially if you've had an herbal cigarette or two. ;-)

Cheers! Rich

Carl & Jerry once did something like this. They had run their car into a ditch and couldn't get it out, and the nearest town was many miles away, and there was no traffic on that road at the time. But, being Carl and Jerry, they had some hook-up wire on hand, so they pulled out the coil wire, stuck in a piece of hook-up wire, and strung about 25 feet of it on the ground; the they took a fingernail file, connected it to the coil primary, and scratched it with a wire conected to +12. (or something like that.)

He then dragged the wire across the fingernail file, scratching out "SOS" in Morse Code. Before too long, somebody came to the rescue.

Of course, it was fiction, but it's entirely plausible.

Cheers! Rich

Hi John, Swimmers are basically small particles in the virteous humor of the eye. A single isn't usually a problem, but if you see multiples, or get them regularly, see an opthamologist. They can be caused by bleeding in the eye (small clots!) that can be indicators of retinal disease or diabetes.

And, back in Optical Systems Class, we used the figure of like 5 photons for a dark adapted eye for detection. Some people are better at this than others. When I was young, I used to be able to run around backstage during a blackout scene change that had everyone else groping around. On the other hand, I was always lousy at baseball. I can't 'see' the ball as it leaves the pitcher's hand. I just guess where it might be. I always figured my eyes had longer than normal integration times...

Charlie

Gee, Charlie. How do you know the grouping wasn't done on purpose? ;-)

I used to be able to spot the single frame commercial indicators in a

16 mm film, when no one else at the TV station could see them.

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

I see lots of them, all the time, but I always have, so it's probably not an imminent problem.

5 photons is impressive, around 1.5e-18 joules.

Some people are better

Makes sense.

John

Of course it is. Duh. It is 100% across the board "this happens to any sighted human".

The point was about how the brain changes its scanning mode on the fly, and has a notable "chemical" delay while it readjusts to normal scan mode.

Your hypocrisy shows your character to be beyond pathetic.

You wouldn't know, I'll bet that NONE of the responders think they are feeding a troll.

You're full of shit. You got caught responding before you found out or was told by another retard.

No surprise there. Most all of your responses are pretty devoid of intelligence, so boredom is not a big leap further down.

Neither does anything else you do, retard boy.

You filter me because I call you a name, yet that is exactly what your retarded ass just spent this entire post doing. You really are pathetic, little brained little boy.

I've had them for years. No comments from the OD about them. The ODs haven't liked the size of my optic nerve cup, but it hasn't changed so they're pretty well convinced it's hereditary. My wife had her vitreous humor separate, which wasn't funny though no permanent loss of eyesight.

Does a 60Hz monitor drive you nuts?

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Hmm 100 photons at say 2 eV each that's 3 X10 ^ -17 Joules. That number means nothing to me. We sell a sonoluminesence thing that's alot dimmer than a battery spark. I wonder how much energy it is???

George H.

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Thanks John, Sometimes when the conversation gets interesting I get afraid the 'fringe' will take over the thread. I'll try and remember to ask the designer of the sono how many photons there are per flash. We sell a PMT with it and he must have some numbers.

George H.

Rods and cones are VERY sensitive.

Ever stare at the tile floor while sitting in the bathroom, and "watching" your rods and cones do their tiny retinal dance, which is like them swaying in the breeze. The patterns in the tile begin to slowly morph and more OR less detail may ebb and flow into the "picture".

No, it wasn't *just* the drugs. I have seen it straight as well. :-)

'bye.

I don't learn procedures, I write them.

I never get headaches, only the occasional aura, and they're sort of interesting.

Vapor only condenses on a part for a couple of seconds. The condensation dumps a lot of heat into the part (stick your finger into the vapor to see how much); once the part gets hot, the condensation stops and any trapped flux stay put. We boil the boards in the deflux agent to loosen any flux, then spray them hard with distilled solvent, probably a hundred time more solvent than could ever condense on the part.

Just like the manufacturer and his rep suggested.

Don't get headaches.

John

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Have you ever used a mill with a rotating table? (Great for making circular O-ring grooves.) When you stop spinning the table the whole thing starts to turn back in the other direction.... Weird.

George H.

Geez, your whole life revolves around elimination.

John

We can only hope that Nymbecile eventually eliminates himself ;-) ...Jim Thompson

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