Stop me if you’ve already heard this one…
If you’re floating inside a perfect sphere, where the inside is made up of a perfectly reflecting surface, and you turn on a flash light … what do you see?
There’s been a few threads on this:
http://boards.straightdope.com/sdmb/search.php?searchid=113665
One thing I didn’t notice mentioned before, and I don’t find any posts with the term:
This arrangement is nearly identical to an integrating sphere. The cited reference isn’t the best introduction to the concept, but it’s clear enough to illustrate the concept.
The only difference is that the inner surface is coated with a perfect diffuser instead of a perfect reflector. The intent is to cause as many internal reflections as possible within the sphere before the light exits. The exiting light is therefore perfectly diffuse, or at least as much as is practical.
Here is another link with some more information about the operation and applications of integrating spheres.
One of the interesting properties is that as a diffuser, it doesn’t matter whether the light source is perfectly at the center of the sphere or shining in thru a hole in the side. Of course, it’s more efficient if the source is inside the sphere so that all 4 pi steradians of the emitted energy is collected, but that may or may not be desired.
Thanks!
Missed that this forum had a search function. 