Need help finding a Scientific toy..

V8TOYTRUCK

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Do you guys know where I can find these things? Its a glass sphere with a base, housed inside is 4 bladed vertical type propeller. Inside the glass there is a vacuum, and when you put this toy up to a bright light, the propeller starts to spin. Anyone have any ideas on what these are called? Thanks in advance.
 

V8TOYTRUCK

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nevermind, I found it.
 

The_LED_Museum

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Ahhh, the Radiometer. I had two of them; an earthquake got one of them.
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The (only) one I have now has two "blades" inside - one side of each is black; the other side has a surprisingly dark picture of Earth on it. I bought one from an online store; the other came off Ebay.
 

B@rt

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A bit off topic, but the Mirage Maker seems to be a great gadget...
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(click desk toys in the link Wits' End provided)
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Anybody who knows anything about it?

TIA,
 

Rothrandir

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bart, that thing is nifty!

at the local mall, there was a kids science shop a while ago with one of those things...the hologram doesn't appear inside the device, it hovers above it resting on air!

yes, there are two bowls that go together as shown and on their insides are mirror-like. any object (up to a ceratin size of course) is projected out the top.
 

Quickbeam

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"Projected" is exactly the word to use.

The same thing happens with any concave mirror, including the countertop ones used for plucking eyebrows. Get far enough away from it and look at yourself in the mirror. The image isn't behind the mirror like a regular mirror, the image is upside down floating in the air in front of the mirror.

The light waves hit the concave surface and are focused to a point in front of the mirror (upside down) in the same way EMR strikes a satelite dish and is focused on the receiver positioned in front of the dish. Your eyes focus on the point where the light waves converge and Voila! you see an image floating in the air.

With 2 parabolic mirrors facing each other (one with a hole in it) the light goes through the hole and strikes the object. That light is reflected off the object to the inner surface of the top mirror, back down to the inner surface of the bottom mirror, and back out the hole making a perfect image of the object (when viewed at an angle) focused at the space made by the hole - and there you see it "floating".

BTW - here's how the radiometer works:

Notice how the sails on the radiometers spin after the light is shining on them. A radiometer consists of a set of vanes, each shiny on one side and blackened on the other.

When the light strikes the shiny surface, most of it is reflected away, but when it strikes the blackened surface, most of it is absorbed, raising the temperature of the surface. The vanes turn because the air near the blackened surface becomes hotter and recoils away, exerting a greater pressure on it than on the shiny surface.

The action of the radiometer depends upon striking a balance between molecular drag and recoil. At higher pressures, drag will dominate and the vanes will fail to spin. At lower pressures, there are too few recoiling molecules to drive the vanes. The optimum balance occurs at a pressure of about 60 mTorr (60 microns Hg).

[edit - further research shows that this is not exactly the correct explanation, but relatively close to what happens]
 

Lighthouse

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Muse & ramble mode >ON<

Crooke's Radiometer I believe...probably dating myself here, but I saved soda bottles for the one and two cents deposit, and purchased my first radiometer years ago via a mail order catalog from Edmund Scientific...showing my age here...this was before they moved to to their then "new location" that had the german submarine periscope in the lobby.

Haven't received one of their catalogs or checked their website in years, but suspect that they still carry radiometers.

Thanks for the push down memory lane. Ramble mode >OFF<
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georget98

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And when you amaze and amuse your family and friends with your radiometer, don't forget to put it under running cold water. It will run the other way.

"Sir, my chronometer is running....backwards."
 

JJHitt

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Originally posted by Lighthouse:
Haven't received one of their catalogs or checked their website in years, but suspect that they still carry radiometers.
<font size="2" face="Verdana, Arial">Sadly, Edmund Scientific as we knew it is no more. They are still in the "optics" lens grinding business under a similar name to the old business, but the "science toy / gee whiz" stuff was spun off into a separate entity and sold.

Or thats How I Seem To Recall It. (I'm sure I'm going to wish I had checked my facts here, but it's SOMETHING like that...)
 

LiteFreek

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Being the scientific toy/gee whiz fan that I am, do you guys have any other particular favorites that you have?
 

whiskypapa3

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Awww...QB you spoiled the fun. There was nothing like the sight of three or four PHDs filling blackboards with formulii, the room with chalk dust and the air with impolite references to each others heritage. Kept them busy while I could get real work done...

When that got old I switched to how that "New SuperGlue worked"
 

Lighthouse

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V8TOYOTATRK: Thanks for the link
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JJHitt: Hey, not to worry, it happens to all of us...some days you are the windshield, some days you are the bug.
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Hmmm,I guess I'm not the only one that spent many hours of childhood daydreaming and ACTUALLY learning neat stuff from their catalogs. >Along with Heathkit and Juliette Electronics catalogs< and being allowed to go with my Dad when he went to Radio Shack back when they were MUCH closer to their roots and surplus parts supply.
 

JJHitt

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You mean back when Radio Shack actually sold "radios"?

Actually my memory isn't totally shot. I found the following in the "About Us" section of their website:

"In 2001, Science Kit & Boreal Laboratories purchased Edmund Scientific. Science Kit, located in Tonawanda, New York, is a leading supplier of educational science products and the largest builder of science kits in the world."
 
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