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## [Fhsst-physics] Optics comments (for now)

 From: Mark Horner Subject: [Fhsst-physics] Optics comments (for now) Date: Sat, 11 Mar 2006 15:42:11 -0800 User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.1) Gecko/20060130 SeaMonkey/1.0

Hi Lindsay


Sorry about the delay, using the hackathon to catch up with things. Comments on the version of optics you sent me, I just flew through and here is a rough list of what came to mind. Filter as you see fit. If you said need table or
figure then I didn't bother repeating that.


In the second paragraph you have a \nts about more EM wave stuff. Don't get into this too much because its the major part of teh modern physics chapter and they will only do that in Grade 12. I think its ok just to state it like you do, or more forcefully as it will be mentioned at the end of the waves chapter which will
come before geometrical optics.


The first sentence after "Properties of Light" we should cut. Birefringent materials material are a classic example of violation of this. Just cutting the sentence doesn't affect the rest of the paragraph.


Here is a list of refractive indices which can be used for the table. Choose the ones you like most. You can say in a footnote or table caption that this is for light with a wavelenght of 589.3 nm and mention that sometimes the speed depends on the wavelenght but they aren't going to learn about that now.

Material        n
Vacuum  1 (exactly)
Helium  1.000036
Air at STP      1.0002926
carbon dioxide  1.00045
water ice       1.31
liquid water (20°C)     1.333
ethanol         1.36
glycerine       1.4729
rock salt       1.516
polycarbonate   1.59
bromine         1.661
glass (typical)         1.5 to 1.9
cubic zirconia  2.15 to 2.18
diamond         2.419
moissanite (silicon carbide)    2.65 to 2.69
cinnabar (mercury sulfide)      3.02
gallium phosphide       3.5
gallium arsenide        3.927
silicon         4.01

The answer to worked example 1 is outside the worked example environment.


Under the Law of Reflection we still need some sort of description of the plane of incidence. I'll look around at digging up a figure but its the first time we say "plane of incidence" and we should just be
clear so that nobody gets confused by it.

Ah - we spell aluminium a little differently ;)


I really like the pstricks images and I'm very impressed that you pushed through on how to make them - I never really got into it.


Here is a trick to make the figure not shift around so they are in the correct sections. We can't expect high school students to actually look for teh figure. Define the figure environemtn with
\begin{figure}[H]


The H means "it must be here" - normally you can do things like htb! which means please try to put it here or at teh top or at the bottom of a page and the explamation means try hard. But the capital H just means put it here regardless of how much it screws other thigns up :)


In the first paragraph of Refraction add a reference to the refraction of waves. Just something like "We know that light is an electromagnetic wave and that waves are refracted when they change medium."


Once again I think the figures are looking good and they are used well to explain things we must just ensure the figure is as close to the explanation as possible. If you don't put the pspicture inside a figure environment it will also be put exactly where you have it in the text but it won't have a caption or be numbered or referencable.


The worked examples in Snell's Law have a minor issue with \westep - it expects you to give it a string \westep{description} which should describe the step. These descriptions are to try to empahsise a global problem solving strategy. Things like the first
step being a unit conversion.


For total internal reflection you can use anything from Wikibooks, even diagram inspiration:
http://en.wikibooks.org/wiki/Total_internal_reflection

We can also steal the pros and cons of fibre from:

http://en.wikibooks.org/wiki/Fibre_optics


Then it gets into the diagram dense part where all the lens stuff comes in. If you use the [H] on figures they'll be able to break
up the text and I think everything will look fine.


For the most part we need more diagrams but the text is looking good and so is the referencing diagrams and the explanations.
How is your time looking? Are you getting quick to make diagrams yet?

Thats it for now.

Good job.

Mark

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