How windows can go from clear to opaque with the flip off a switch?
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I’m trying to figure out a good analogy for this to ELI5. The effect is something like changing the tilt on blinds, but the rearranging is happening on a molecular scale.
A little electricity passing through it excites all the electrons in a thin layer, which causes them to jump up into the layer above. That changes the ions present in each layer. Molecules interact and orient to each other based on the movement of and availability of electrons. With the electrons in an excited state, the orientation of the ions is not completely transparent, causing the darkening effect. When you turn off the current, the electrons return to their original place and the materials realign into an almost fully transparent arrangement.
Usually there are two or three pairs of these layers in a film applies to the glass window in order to increase the total effect.
When I was a kid, there was a primitive kind of electronic game that used LCD displays capable of effectively 1 color. The display was transparent, but had sections that, if powered, would turn black. That mechanism was placed over a sticker, so you could play a baseball game and pre-stamped parts of the display would light up to show you what players were on base, etc.
That’s also how you can make a window that can change its tint. They’ve got a film with that kind of display on it. When there is no electricity, it’s transparent and you can see through the window. When a certain voltage is applied, the film turns dark and you can’t see through it. Depending on how it’s made, you might be able to apply partial voltage and let *some* light through: this lets you “dim” the tint.
As far as I can tell it’s pretty expensive, but it definitely looks cool.
Smart glass is full of liquid crystals. When your turn the switch on, electricity makes those crystals align so you can see trough the them. When the switch is off the crystals roam free again, making the glass look blurry.
The magic of polarization!
You’re going to need props for this, go grab two pairs of sunglasses.
When you look through one the world is a bit dimmer
Take the second one and hold its lens in front of the first and rotate it. If they’re polarized glasses you’ll discover that the amount of light let through depends on the angle that the second pair is rotated. If you only have 1 then look at an on TV/monitor through them while you rotate them and you should get a similar effect.
Polarized glass means that light can only make it through if its wiggling in the correct direction like up/down or left/right but an up/down polarized sheet will almost completely block light that is wiggling left/right
If instead of sunglasses you have a clear panel of up/down polarized glass then most of the light will make it through just fine and will all be oriented up/down. Apply a layer of liquid crystal which can be made to change its polarization direction with an electric charge. When its off and polarized up/down then you don’t see anything different because the light is already polarized that way. As you apply more voltage it rotates to be polarized left/right blocking an increasing amount of light until it is 90 degrees off from the polarization of the glass and blocks close to all the light coming through
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