# Levitating Metal with a Solar Cooker: A Feasibility Study

• Misc.
• dansmith170
In summary, a solar cooker can be used to levitate a piece of metal using a focused beam of sunlight. The foil will do every possible trick to move to sides and rotate - leaving the beam.
dansmith170
TL;DR Summary
I would like to build a solar cooker that can levitate a thin piece of metal using sunlight, will it work?
I would like to build what is usually used for heat production and is called a solar cooker. However, I would like to use it to try to levitate a piece of metal.

Here are my assumptions:

A. aluminum density = 2.7 g / cm^3
B. Sunlight intensity on Earth's surface is about 1000 W / m^2
C. aluminum thickness = 2.5 micrometers (https://geistnote.com/2-5-m-aluminum-foil/)
D. Aluminum area = 1 centimeter squared
E. solar cooker area = about 2 square meters
F. acceleration due to gravity on Earth = about 9.9 meters / second^2
G. I take it that some kind of lens maybe be necessary to focus the light reflected off the solar cooker to a smaller area of about 1 square centimeter.

If my math is correct, I think the force of gravity on aluminum with the aforementioned specifications equals about 6.6 microNewtons. The force of sunlight focused from the solar cooker to an area of 1 square centimeter equals about 12 microNewtons. So, the resultant net force on the piece of aluminum foil should be about 6 microNewtons and should be directed skywards. This should cause the aluminum foil to levitate or move in the skyward direction, counter to the direction that gravity would otherwise cause it to move.

Does this sound like it could work? I guess one concern I have is whether this much focused light would melt the aluminum foil.

dansmith170 said:
Does this sound like it could work? I guess one concern I have is whether this much focused light would melt the aluminum foil.
You must carry out the experiment in a vacuum, or the aluminium would instantly burn in the oxygen of the atmosphere, then rise as a thermal plume.

If you use a lens, the lens will get hot because it is not perfectly transparent at all wavelengths. Use mirrors that radiate heat from their back surface.

dansmith170 said:
G. I take it that some kind of lens maybe be necessary to focus the light reflected off the solar cooker to a smaller area of about 1 square centimeter.
The Sun has a diameter of just over 0.5 degrees when viewed from the Earth. You will need some fancy optics to concentrate that area of energy to a point, then collimate it to be a parallel beam, pushing in one direction.

russ_watters, BillTre and berkeman
The foil will do every possible trick to move to sides and rotate - leaving the beam.

russ_watters and Tom.G

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