Beetle in a Geißler tube - Page 1
Forum section: electronics / projects

author: Physikfan
author_rank: Regular Contributor
timestamp: November 06, 2017, 07:25:42 pm
content: The three pictures show a beetle in a Geißler tube:(DC source, 9 kV, cathode top, anode bottom)Exposure normal, with room lighting, fluorescence on the glass wallExposure 2 f-stops underexposed, room dark, fluorescence on the glass wallExposure 2 f-stops underexposed, room dark

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: November 06, 2017, 07:47:00 pm
content: Wow, stunning! Why does it glow? I love geißler tubes (still looking for one for my tube collection)and know how they work, so I am very interested in what makes the beetle glow like that.

author: Gyro
author_rank: Super Contributor
timestamp: November 07, 2017, 10:08:54 am
content: The legs, eyes etc. have almost certainly been painted with phosphors to make them stand out. This is quite commonly in other tubes - eg. dots on the paddles of Crooks railway tubes...https://duckduckgo.com/?q=crooks+railway+tube&iar=images&iax=images&ia=images&iai=http%3A%2F%2Fwww.infogr.ch%2Froehren%2Fcrookes6%2Frailway_1_06.jpgP.S. A stunning specimen.

author: amyk
author_rank: Super Contributor
timestamp: November 07, 2017, 11:27:58 am
content: It is not a real beetle, but a model painted with phosphor. Here's a similar tube with flowers instead:http://www.giangrandi.ch/electronics/geissler/img008a.jpg

author: Gyro
author_rank: Super Contributor
timestamp: November 07, 2017, 11:44:33 am
content: I wouldn't be 100% sure. The flowers, certainly, but a well dessicated beetle, maybe.These tube work on the basis of not being a 'hard' vacuum, so it's possible that itcouldjust be a real beetle - that's unless the legs would fall off too easily!Tubes with mineral samples were common too.EDIT:There's very little doubt about the Dead Parrots thought!https://www.ebay.co.uk/itm/9-Crookes-Fluorescent-Parrot-Tube/362151402889?hash=item5451e7dd89:g:93sAAOSwuspY9V4K

author: StillTrying
author_rank: Super Contributor
timestamp: November 07, 2017, 05:17:25 pm
content: Why are the legs glowing most brightly just where they join the body, and not at their ends?

author: Physikfan
author_rank: Regular Contributor
timestamp: November 10, 2017, 07:04:00 am
content: Beetle in daylight without discharge:

author: Gyro
author_rank: Super Contributor
timestamp: November 10, 2017, 09:05:33 am
content: Hmmm, it does look more like a model in daylight, probably just my wishfull thinking. It does appear to be impaled on the electrode though.You can see the powdered phosphor coating now.

author: texaspyro
author_rank: Super Contributor
timestamp: November 10, 2017, 09:42:30 pm
content: A lot of inscts glow under UV light. Scorpions are particularly good at it and the normal way of hunting them is to use a UV flashlight at night.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 10, 2017, 10:01:37 pm
content: Assuming it in not fake, I suspect it might be a protein component of the insect's exoskeleton. Proteins can be fluorescent, like GFP.Here's a link about insects:https://www.hindawi.com/journals/psyche/2011/875250/

author: Gyro
author_rank: Super Contributor
timestamp: November 10, 2017, 10:11:23 pm
content: I'm not sure that would guarantee them flourescing under direct electron bombardment in the 'vacuum' tube though.

author: texaspyro
author_rank: Super Contributor
timestamp: November 10, 2017, 10:15:57 pm
content: Quote from: Gyro on November 10, 2017, 10:11:23 pmThere's one way to find out... one experiment is worth 1000 opinions.I can probably score the scorpions, but, alas, no tube-a-ma-thingy.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 10, 2017, 10:20:01 pm
content: Or maybe compare different orders/families of insects, such as hymenoptera (bees.wasps, etc) to roaches and beetles.

author: texaspyro
author_rank: Super Contributor
timestamp: November 10, 2017, 10:28:51 pm
content: Quote from: jpanhalt on November 10, 2017, 10:20:01 pmAnd don't forget kittens, puppies, and small children

author: jpanhalt
author_rank: Super Contributor
timestamp: November 10, 2017, 10:30:36 pm
content: I was being serious.Your point?

author: texaspyro
author_rank: Super Contributor
timestamp: November 10, 2017, 10:36:08 pm
content: Quote from: jpanhalt on November 10, 2017, 10:30:36 pmEnquiring minds want to know! Plus nerd humor.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 10, 2017, 10:42:29 pm
content: You obviously lack both. Do you have even a basic understanding of the differences between insects and vertebrates?

author: texaspyro
author_rank: Super Contributor
timestamp: November 10, 2017, 10:51:12 pm
content: I apologize if my nerd humor offends you.Oh, and I'd never pump down a bee... I'm rather fond of bees. I have used roaches as vacuum gauges before.

author: Physikfan
author_rank: Regular Contributor
timestamp: November 11, 2017, 07:11:44 pm
content: Hi StillTrying"Why are the legs glowing most brightly just where they join the body, and not at their ends?"I assume that the electron beam intensity is not uniform enough over the whole area of the beetle.To prove this, I will stick a small magnet to the wall of the tube, forcing the electrons to take a new path.I think we will then see a different distribution of brightness on the beetle.

author: Physikfan
author_rank: Regular Contributor
timestamp: November 12, 2017, 03:29:54 pm
content: Bottom of the beetle in daylight without discharge:

author: Gyro
author_rank: Super Contributor
timestamp: November 12, 2017, 04:38:44 pm
content: Well that probably resolves the question - thanks for keeping us guessing