# Few Questions about building a Solar Oven.

Pinu7
I hope I am posting this on the right section...

In my Environmental Science Class, we are to design and build a solar oven(without using solar panels!). We will be baking a cookie.

Me, being a "mathematician", remembered something about a parabola, that if light ray hits anywhere on the interior surface, it will reflect through its focus. I assumed for realistic three dimensions, this will work for a circular paraboloid(confirm that please). i.e. zr^2=x^2+y^2

If I put a cookie at its focus, it should cook well(or ignite).

The surface of the circular paraboloid will be reflectable

I have a few questions-

1. How exactly DO I create the frame of a circular paraboloid? I can't just stare at my calculator and yell "materialize!"

2. What material should I use that has a high albedo, but is cheap-ish? I will spend no more than $30 on this. 3. How will the size of the paraboloid effect the heat of the cookie? THE HOTTER THE BETTER. I want a high powered oven, if the cookie turns to ash, I'd be ecstatic. ## Answers and Replies Science Advisor You are right about the parabola first of all. Remember many many years ago when we first started learning about complex shapes. Remember the concept of a locus (loci?? sp?). Anyways, the locus of a parabola is a group of points that lie equidistant from a point and a straight line. See the wikipedia page for a proof showing the favorable reflective properties. Anyways, having seen a man win$100k for a solar oven, I briefly looked at some designs. Unless you want to spin a large amount of liquid metal into a parabola, you're going to have discretize it (for lack of a better word). A common design that I've seen it referred to as a Parvati Parabolic Cooker.

Check out this site which has pretty good instructions for how to make a type of oven.

http://www.angelfire.com/80s/shobhapardeshi/ParvatiCooker.html

It seems that a common way to do this is to include a black box which will absorb the heat. Good luck,

Pinu7
Okay thanks, now I other questions.

Should I place glass at the top of the paraboloid to insulate the oven, or will light be dimmed too much?

Should I put a rod from the bottom point to the focus and putting a small level platform on it because I will be baking ONE cookie?