Doesn't look like much, does it? It certainly didn't look like much when Debbie pulled hers out at year two camp at Rowan University a few years back, but it was fascinating enough that I hunted down one of my own.
What you see there is a piece of fiberoptic glass, flat on top and bottom and tapered from a circle at the 'bottom' to a widened rectangle at the top.
With no batteries, no source of external light, it either magnifies (if the widened end is upward) or shrinks (if the narrow, circular end is upward) the image underneath the glass. In enlarging, it does seemingly fade the image a bit - which makes sense as the light is being spread out. In shrinking the image, it almost 'densifies' or 'concentrates' the image which again makes sense to me.
I haven't found a great way to use this item in our material science curriculum as much more than a neat curiosity object, but it's fascinating to have.
And, in case you wanted to take the route I took in trying to find one of your own, here's the info printed on the back of the magnifier.
This might be my prize material science possession. It's three pieces of silicon.
The Lego figure is just there to show some scale. I figure everybody knows how big a Lego minifigure is, especially Margaret Hamilton.
These were sitting in the back room of the original Princeton High School building before it was torn down. During the last year in the building - as we transitioned across the street - we were doing a lot of paring down, preparing to move what we needed and leave the rest behind for a public auction. This was on the shelf of another science teacher's storage room and was clearly bound for the auction. They didn't know what it was, didn't want it, didn't think it had much value.
And I grabbed it with great gusto.
I wasn't letting this one go because I know I'll likely never get another chance at it.
You can see the process of producing mono-crystalline silicon in videos I've posted before. The silicon has to be refined before this (something I got to see done outside of Butte, Montana - but where they didn't allow any photos, sadly). That results in something like the rough chunk in the front, left of the photo. This chunk is roughly small-fist sized.
That chunk - and a bunch more like it - is melted and a single silicon crystal is lowered into the rotating vat of molten silicon. The single crystal is slowly raised from the surface of the molten silicon, rotating in one direction while the vat is rotated in the opposite direction. If the conditions are just right, an single crystal of silicon is raised from the vat. That's what the tower is in the photo above. The final product was likely taller and didn't end in a flat bottom layer but rather a second tapered end.
Check out the process from about 1:00 - 3:00 in the below video.
The tower (technically a pull of silicon) would then be sliced into flat wafers that would then be etched into computer chips.
As to how Princeton High School got the silicon tower and chunks...I'm not entirely sure.
I've heard from a couple of non-PHS teachers that Cincinnati had a silicon wafer production facility that shut down and donated silicon samples to local schools, but I haven't been able to track down any information about that donation. I did find information about two silicon wafer production facilities in the Cincinnati area. One was near Maineville, but that one closed down in 2010. That's too late to fit into our timeline. The other, now known as Milacron, produced silicon wafers in the 1970s-1990s ("by 1984, the Mill had become the world's largest supplier of this type of wafer.) While I don't have any proof, that fits the timeline of a possible donation to Princeton much better. So I'm assuming we have Milacron to thank for this donation.
Most of it is about the mathematical proof that spheres cannot be packed to occupy more than 74.05% of a volume. There's a lot of math and handwaving involved in that proof.
The part that fits with what we teach about material science is from about 1:30 to 6:30. After that it gets into the proof.
I am curious about one thing, though. At 4:53 he shows something that he says is the smallest part of the crystal that can repeat to form the entire crystal. I would normally think of that as the unit cell, but I've never seen that specific image as the unit cell for FCC - which is what I think is being shown. Can anybody help clarify that for me?
The chemistry happening here is serious but incredibly important. It's a great application of Ksp if you get into that in chemistry (especially AP chemistry).
There's a coating of lead with orthophosphate...if you add enough orthophosphate to keep the coating constant. At least there should be that coating. There was before the water source switched because the Detroit water system added orthophoshpate.
Then there was too much chlorine in the water - river water picking up run-off salt. Then they added disinfectants with even more chlorine - which reacted with the iron and lead to inactivate the disinfectants and draw more lead into the water. So they added more chlorine.
And they caused a problem that they solved with more chlorine.
But I thought there was a carbon cycle to recycle things.
Among the hundreds of other problems that need to take place in our recycling streams, there's another one that's needed - finding a way to identify black plastic. According to the above video, the black plastic isn't recognized by the IR-light sorting device as plastic at all.
