| Making the solar mirror is simple. The | | | | This is where potato chip bags come in |
| materials you need are: | | | | handy. It's a cheap way to make a shiny |
| · A rotating platform on top of which a | | | | reflective surface. |
| container can rotate | | | | Clean out the inside of the chip bag |
| · Plaster-of-paris (roughly 2.5 litres | | | | with detergent. Then cut pie shaped |
| or 2500 mL) | | | | pieces out of it and glue them onto the |
| · A container with inside diameter | | | | surface of the dish, shiny side up. This |
| roughly 10.5 inches | | | | will create the mirror surface. |
| · A large potato chip bag (with shiny | | | | When the sun is out, orient the dish so |
| metallic surface on the inside) | | | | that it directly faces the sun. The |
| The liquid plaster-of-paris will be | | | | focal point will be roughly 5 inches |
| placed inside the container, and the | | | | from the bottom. You can test this by |
| container will be made to rotate about | | | | moving your finger along the space above |
| its center at roughly one revolution per | | | | the center of the dish until you feel |
| second. Due to the nature of the | | | | the hot spot. That's your focal point. |
| physics, this will cause the surface of | | | | It can get very hot so be careful. Using |
| the plaster-of-paris to form a parabolic | | | | a digital kitchen thermometer I measured |
| shape. Upon hardening, the plaster will | | | | a temperature of over 200 degrees |
| retain this shape. | | | | Celsius! |
| To make the rotating platform you may | | | | This is a small-scale example of |
| have to get creative. One way is to get | | | | concentrated solar energy. Clearly, |
| an old turntable and place the container | | | | there's serious potential for future |
| on top, or use a motor-gearbox-pulley | | | | energy needs. |
| combination to rotate the container at | | | | If you would like to see pictures of the |
| one revolution per second. | | | | parabolic dish with explanation |
| Once you've made the plaster shape, it's | | | | included, then feel free to visit the |
| time to create a mirror surface on it. | | | | link below. |