(May 31, 2015 at 9:19 am)Neimenovic Wrote: In this episode of sciency gifs





^^^ EXPLAIN ^^^

The speed of light is different in glass than in air. That leads to a change in direction when the light enters/exits - because neighboring lightwaves get shifted in speed a bit later than others if the beam of light they make up does not enter the glass nicely perpendicular, and that leads to a change of the orientation of the waves.

Since the speed of light in materials usually depends on the frequency of the wave, roughly speaking bc the electrons in the material can follow some frequencies more easily than others, the amount of change in direction depends on frequency, i.e. color.

Here is an illustration why going into a slower medium at some angle leads to a change in direction


Because of the reduced speed in the glass, the distance AE is shorter than BC, so the beam changes direction.

Snell's Law, twice in one thread!!!

(May 31, 2015 at 9:19 am)Neimenovic Wrote: In this episode of sciency gifs

^^^ EXPLAIN ^^^

So the glass of water acts just like a curved mirror. It bends the rays of light towards each other, and if the focal point of the two rays is in front of the arrow, then what you see is a reversed image. You can see this effect in a magnifying mirror or magnifying glass. As you move away, suddenly the image you see will flip.

Let me see if I can find a graphic... google.... aha!

(May 31, 2015 at 9:19 am)Neimenovic Wrote: PIn this episode of sciency gifs







^^^ EXPLAIN ^^^

When the glass is empty, light going through the glass gets refracted at 4 separate optical density interfaces in two pairs, as it goes through 2 sides of the glass.   Necause the surfaces of each side of the glass is approximately parallel, the pair of refractions as light goes through a side of the empty glass are mutually canceling.  This cause you see an upright image, as if you are looking through double pane glass window.

Pour in water and the optical density interface on the inside of the glass became a much less dramatic, and refraction of light entering from air into glass and from glass into water no longer mutually cancel, the refraction from glass into water being much less than the refraction of air into glass.    So the main refraction activities occur only as light enter and leaves the entire glass.   Now it is possible to approximate the glass as a solid convex lens. So you see an reversed image, as if looking through a magnifying hand lense held a considerable distance from the eye.

Ok, ta for the explaining....pretty sure that's over my daily limit of sciency words but whatev

I wanna know what that poofy blue stuff is!

I don't have a spiffy gif, but my question is light related and its happening as I type this. Lets see if I can describe it well enough to get an explanation.

So, I've just laid down in bed and I took a peek at my phone. I suddenly see something out of the corner of my eye: three shiny shapes. I moved my phone to shine light on what I'm seeing, but before my makeshift flashlight got to the shapes, they disappear. I shine my phone back into my eyes and the shapes are back. So, I shine my phone on the shapes and see that it's the reflected strips on the vest I have to wear when I go to a job site for sampling. Furthermore, as I slowly angle the phone to shine in my eyes, the reflected surfaces slowly grow more visible.

Now, the first thing I thought of were cats eyes, or any animal that has more reflective eyes, but this is sort of the reverse of that. What is going on exactly?

My thoughts on this is that reflectors are really good at making low levels of light visible against non-reflective material. But just like a reflective vest doesn't look reflective in the daytime, when you shine a bright light at it and the surrounding areas, it washes out just the same. I'd bet that there's something just reflective enough behind you to throw some light from your phone's screen back onto the reflectors, visible in your periphery.

But that's just a spitball.

(May 31, 2015 at 5:55 pm)Neimenovic Wrote: I wanna know what that poofy blue stuff is!

Apparently it's called Heatswell. It's a coffee cup sleeve replacement idea. The GIF is a proof of concept, but it doesn't actually swell that much as a product. You can actually choose how much you want it to swell. (You can also get it to swell in different patterns, like a Starbucks logo.) It supposedly feels like a terry cloth towel when it swells.

Ah, coolness! Thanks Steely, I can sleep sound now

(June 1, 2015 at 12:50 am)SteelCurtain Wrote: My thoughts on this is that reflectors are really good at making low levels of light visible against non-reflective material. But just like a reflective vest doesn't look reflective in the daytime, when you shine a bright light at it and the surrounding areas, it washes out just the same. I'd bet that there's something just reflective enough behind you to throw some light from your phone's screen back onto the reflectors, visible in your periphery.

But that's just a spitball.

That's a good spitball. I didn't think about maybe something behind me scattering light, but I did shine my phone on the low slanted white ceiling in my room, and still couldn't see the vest. The vest was to the left of me and the ceiling was to the right. So maybe something to do with the orientation of the light source, eyes, vest, and scattering surface may have something to do with it.

What it seemed like was going on was that shining light into my eyes somehow magnified the reflective vest. Another idea could be that when you shine light into your eyes, the surrounding area appears to get darker, so perhaps I somehow darkened everything, but the vest, making it suddenly visible.