This only tangentially fits here but how often do you get to use the phrase:
in public? Indulge me, please?
My best friend from high school and I were sitting around one afternoon shooting the shit, when the subject of Van de Graaf generators came up briefly. We’re both of the same bent of mind and that was not surprising. But later that day, we trucked over to my girlfriend’s house to hang out for a bit and a Ouija board made an appearance. Now, anyone who’s anyone knows how a Ouija board actually works. Except my gf’s younger sister …didn’t. Best friend and I sit down to summon some spirits, gf’s sister is too scared to take an active part and gf is so hard you can hear them rolling around in her head; she was extremely no-nonsense.
The questions began: Is anyone there? Straight to “YES.” Will you talk to us? Spells out “Y-E-S” (nice touch). Gf’s sister is getting obviously distressed. Is there anyone here you would like to address directly? Spells out gf’s sister’s name! She gives a small shriek and says she isn’t talking to anyone “from beyond.” The planchette spells out “I will predicate Van de Graaf”! Gf’s sis: what does THAT mean? Me: “Predicate” means ‘will make happen’ (not true), Van de Graaf is a machine that makes lightning bolts indoors and if you touch it, your hair will stand on end and you may not survive. Gf’s sis runs from room fretting big time. Gf says: Thanks loads, you jerks, I’ve got to get her settled down after you’ve left. At which point she tossed us out into the night.
Keeping a straight face during all this was very hard, bit it was fascinating how the planchette actually seemed to work on its own. God knows what our warped minds would have thought up and Ouija-ed if we’d had a little more time.
Browsing through this thread reminded me on one experiment that I think I’ll have to declare my coolest, just because it’s so simple, and can be so effective.
Empty aluminum drinking can.
Splash of water in the can.
Heat to boiling and boil until most of the water is evaporated.
Quickly upend into glass dish fill with water.
POP! One drinking can squished almost completely.
My high school chemistry teacher did that one, except he used a heavy-duty metal can similar to the metal gasoline cans or paint thinner cans of old. The key is to seal the can so that a vacuum can form inside.
I’m sure that is even more spectacular. The cool thing with the beer cans is the pressure changes so quickly water can’t flow into the opening quickly enough and atmospheric pressure crushes it before much water enters.
Our high school chemistry teacher used the Bunsen burner gas jets to heat up the room on cold mornings. Not the Bunsen burners themselves, just the valves sticking out from a long pipe that ran the length of the countertops. So every 3 feet along the wall was a 2 foot flame blazing horizontally towards you. It was like sitting in a crematorium.
The best experiment he did was making that iodine compound that explodes at a touch. But he did a fairly large sheet of paper among the small pieces and accidentally set some books on it. It threw them into the air with a deafening boom.
In an early college physics class, the lecturer attached a steel can to an electromagnet, its one open end pointing to the side. On the other side of the room he aimed a length of pipe at the open end of the can, and put a small switch at the end of the pipe. He then put a metal ball into the pipe and blew on it. The ball shot out of the pipe, triggering the switch which made the electromagnet let go of the can. The can fell straight down about three feet, and the ball followed a curved trajectory to the can. Then the ball entered the can, sweeping it sideways. He was demonstrating that the paths of the objects can be planned by calculation.
Here’s a couple, under the category of “playing with fire at home.”
Squirt a little lighter fluid into an empty drink can. After a few seconds, enough vapor will be present that a lit match over the top will give you a quick jet of flame that whistles “floop!” It puts itself out when the oxygen’s gone, but a few seconds later you can do it again, and again until you’re bored.
Tie a plastic bread bag into a row of knots. Then take it outside, to the top of a ladder in the dark. Hold one end of the tied bag, and light the other end. As the plastic melts, it will start to drip to the ground. The multi-colored flaming drops will make a musical “voop, voop, voop” as they fall. I think this would be entertaining under normal circumstances, but with the chemical contents of our brains at the time, it was spectacular and hilarious.
While not exactly a true demonstration, he did use visuals.
20+ years ago, at the safety seminar we somehow managed to get a speaker from an out-of-state electric company. He was a good, engaging speaker & made as lively as could be (You try to get a ½ hour or 45 mins out of 'Electricity transmission wires are dangerous" & the rule of thumb that the higher the wire is on the pole the more dangerous it is).
He finishes the lecture with, "To sum up…
(Holds up small insulator) - “Open casket”
(Holds up medium-sized insulator) - “Closed casket”
(Holds up large {high tension} insulator) - holds up hand, palm up…blows across his hand
A co-worker of mine was fond of mixing alkali metals (sodium and potassium) with halogens (bromine). Anyone with a rudimentary understanding of the periodic table knows this is not a good idea. He tried it in front of his class and the flask exploded. Bromine got on a girl’s clothes. He was lucky he didn’t get fired that day, and his contract was not renewed for the next year.
I just read that unwinding adhesive tape generates T rays. This absolutely HAS to enable some unspeakably cool educational demo.
T rays are electromagnetic radiation in the wavelength range from 0.1 to 1 millimeter. This is still a difficult part of the spectrum to use, in between microwaves and what most regard as infrared radiation. Electronics are generally too slow to generate or detect T rays, and not much radiates here, except the very weak thermal radiation from pretty much everything. The fact that peeling adhesive tape generates T rays is a pretty nifty find.
By the way, peeling adhesive tape also generates light. This can be pretty surprising, but it’s easy to test. Get into a dark place and pull masking tape or electrician’s tape or duct tape or Scotch tape, staring where the point of separation is. You’ll see light!
Yes, the tape peeling light generation is triboluminescence. I don’t know that the T ray generation is considered triboluminescence, though, because T rays aren’t luminescence, they’re not light. But it is said to be a tribological effect.
I remember this example from my Physics I book and a similar in-class demonstration. The idea if that if you aim at a monkey sitting on a tree branch, and the monkey doesn’t move, you will miss it. However, the monkey hears the shot go off, lets go of the branch, and is hit every time. The speed of the dropping monkey equals to the speed of the dropping bullet, due to gravity. This The Monkey and the Hunter site explains it better.
Isn’t that splitting hairs a bit? The EM spectrum is a continuum, with visible light only being one small band of frequencies. So I’d think if it’s not triboluminescence, it’s something very similar.
I agree that it’s something similar to triboluminescence in every regard except where on the spectrum it falls. As to whether that’s splitting hairs, well, that’s a deeper question about how important various elements of the definitions of light and luminescence are.
I did just check, and the definition of luminescence is specific to light. Definitions of light, and articles about light, exclude T rays by virtue of wavelength limits or the requirement that it be visible.
Is it worthwhile to have a word such as “triboradiation”, like triboluminescence but without the restriction to visible wavelengths?
so hard you can hear them rolling around in her head; she was extremely no-nonsense.