Day+16+em+spectrum


 * Day 16 - the em spectrum**

We spent some time considering the basics of light: reflection, refraction and splitting white light into a spectrum. Don't be lulled by the apparent simplicity of these topics - students can ask some difficult questions. Simply asking 'what actually //is// light' is enough to make most non specialists' heads explode. It's a good idea to have gone into the physics of transmission, reflection and refraction in terms of physical models. This is a good start at explaning how light is transmitted through a transparent medium, also covered in this piece from How Stuff Works.

There's a passage in '[|The Physics Classroom]' that deals a little bit with reflection, after that, I've not yet found much that's a huge improvement on the Wikipedia page. Disappointing - if anyone finds anything better, please add a link.

Bizarrely, the most useful and concise bit of support on refraction at a higher level that I've found is on a website for scuba divers -it's called scubageek - no arguments on the choice of title here! Ah! This is better: There's a nice discussion in the New Scientist about why light refracts. Essentially the argument seems to be that the transmission model for light passing through a material says that it slows as energy is absorbed and then retransmitted by bonds in the material. There's also a bit of discussion as to why blue light is bend more than red - to do with resonant frequencies of certain bonds in solids and liquids. On the subject of slowing light in a medium, did you know that you can slow light down by a factor of one milllion, stop it completely and even 'teleport' it? Welcome to the freaky world of Bose-Einstein condensates...

There's some information about prisms and the visible spectrum here on "From stargazers to starships" We spent a little time discussing why rainbows are curved - nice discussions here from Scientific American and How Stuff Works

Diffraction is fairly easy to model. You'll need to get your head around this because it's going to come up agian in the infamous double slit experiment. There's a good introduction here on 'About' and some more detail on this site from the University of Tennessee - interesting side note here - UoT have awarded only two honorary doctorates, one being to Dolly Parton. Besides a stringent policy on honorary doctorates, they have a pretty reasonable physics website, well worth a look on other topics.

Resources and links below, please. Careful that you don't overwrite someone else's changes. If in doubt add a new page and link to it later, I'll tidy if needed.

This is the link we used in the lesson today to explain diffraction of waves [] - Sejal