# Few Questions about building a Solar Oven.

1. May 18, 2009

### 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. 2. May 19, 2009 ### minger 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,

3. May 19, 2009

### 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?

4. May 20, 2009

### minger

Glass on top contributing to a "greenhouse" effect may be good. There's only one way to find out!