## April 07, 2006

### Lasers, Mirrors, Water, and Pure & Unfiltered Hatred

Before Spring Break we got a neat project assigned in Physics called a "Laser Race". Essentially, there is a course and a bunch of obstacles. The laser starts from a fixed position and you have to use mirrors and refraction tanks to guide the laser around the obstacles, perhaps hitting a bonus or two, and eventually hit a target. Depending on how close you get to the center, that's the grade you get. You have to use two mirrors and one refraction tank, but you can add up to two mirrors for 5 extra credit points each and 1 refraction tank for ten extra credit points. Anyways, we had to work in groups of 2, my partner was Jake. We laid out our course during class and then when I went on my trip over break Jake did all the calculations and set-up. "Hold on" you say, "What's a refraction tank?!?!?" Well, let me tell ya, it's more difficult to work with than a mirror. Here's how it works. . .it's a dish shaped in a half circle filled with water. When a laser enters the flat side at an angle it bends through the water, coming out at a different angle. There's a calculation for finding the angle it enters and the angle it leaves. Here's a little graphical representation: You know angle "i" but you need to find angle "r", here's the equation. There's a reason I'm telling you all of this, and here's that reason: We screwed up. Our first problem is that our original setup used 5 mirrors, one more than we were allowed. The second problem is that Jake inverted the equation he did Sin[r] over Sin[i]. So, basically, our course was hosed and the coolest part is that we didn't discover this until the lunch period before the laser shoot. That gave us about 12 minutes to either
1. Fix our course
2. Make a new one

Vihang said...

You could've improvised and used 4 mirrors ...
See ..
http://img176.imageshack.us/img176/8998/4mirrors2tankshh5.jpg

And yeah I'm used to teachers being unfair just because someone realized that the refractions can be easily canceled.

Vihang said...