Solar Hot Dog Cooker
is for older students or for younger students with adult supervision.
A reflective hot dog cooker can be built from a cardboard box, tin
foil, and posterboard. Sunlight hits the reflective surface and focuses
on the hot dog held in the center. Students can work in pairs or individually
if there are enough materials.
- Select a long narrow box; the longer the box the more heat collection
is possible. Choose a focal length between 5" and 10" and design
a parabolic curve as seen in the picture. One template could be used for
all the cookers. Trace the curve on the open end of the box so that it
is centered and straight.
- Cut out the curve with a utility knife. Stress the importance of being
exact. Measure and cut a piece of posterboard that will fix flush against
the opening to the box. Attach this with tape beginning at the center and
working toward to edges.
- Cover the curve with white glue and apply aluminum foil shiny side
out. Start in the middle and smooth toward the edges. Try not to wrinkle
or fold the foil; you want it as smooth as possible.
- Use two scraps of cardboard taped to each side as supports. Using the
sun or a projector light, test the focal point. There should be a bright
spot where light is concentrated; mark this spot and punch a hole for the
skewer. Use a section of a coat hanger from which the paint has been removed
for a skewer.
- Enjoy your hot dog!
Hot Enough to Fry an Egg
You can also use the heat of the sun on a sidewalk or on black asphalt.
Take three eggs, two black/cast iron frying pans, and one piece of thick
glass to cover one of the frying pans.
Put one egg directly on the sidewalk, one in the pan without the glass
cover, and one in the pan with the cover. Which one do you think will fry
the quickest. Make sure you clean up afterwards!
See one young man's experimentation with solar cookers for a
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