Snake
Posts: 3
Joined: Tue Feb 06, 2007 1:07 am

Solar Concentrator

I intend to construct a large parabolic reflector made of Mirrors, plywood, Acrylic Ball Joints, Etc. What I wish to ask is some sort of way that I can correctly measure the angles for a focal point, maybe 6 in- 2 ft away from the central mirror. Any Ideas?

zzzzdoc
Former Expert
Posts: 238
Joined: Thu Jan 05, 2006 6:28 pm
If you do a search in Wikipedia on parabola, you will come up with the mathematical formulas for the focus point of parabolas.

http://en.wikipedia.org/wiki/Parabola

We're not sure what grade you are in, but the formulas have mostly been simplified to algebra, and aren't that difficult.

Hope this helps.

Alternatively, you can build a parabola and check the focus point by pointing a laser pointer at it, but be careful that you cannot accidentally be looking straight at the laser, which can permanently hurt the retina in your eyes. I would use that as a plan B.
Alan Lichtenstein, MD
Anesthesiologist

Mens et manus
Veritas

He who laughs last...Thinks slowest.

Louise
Former Expert
Posts: 921
Joined: Mon Jan 16, 2006 2:17 pm
zzzzdoc wrote:If you do a search in Wikipedia on parabola, you will come up with the mathematical formulas for the focus point of parabolas.

http://en.wikipedia.org/wiki/Parabola

We're not sure what grade you are in, but the formulas have mostly been simplified to algebra, and aren't that difficult.

Hope this helps.

Alternatively, you can build a parabola and check the focus point by pointing a laser pointer at it, but be careful that you cannot accidentally be looking straight at the laser, which can permanently hurt the retina in your eyes. I would use that as a plan B.

If you do use a laser pointer, use a red one, not a green one. Also, the cheaper the laser pointer, the less bright it is (generally).

Louise

zzzzdoc
Former Expert
Posts: 238
Joined: Thu Jan 05, 2006 6:28 pm
The laser pointers are also labeled as to which class of power they emit. The lower/lowest, the better.

You should try to catch a rerun of the Mythbusters episode where they made the Archimedes Death Ray (there are actually 2 episodes, the original, and the one where the guys from MIT come down to melt one for Big Gray.)
Alan Lichtenstein, MD

Anesthesiologist

Mens et manus

Veritas

He who laughs last...Thinks slowest.