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Q & A: light between mirrors

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Most recent answer: 12/19/2016
Q:
Why doesn't a lighted enclosed space with reflective surface stay light when light source has been extinguished?
- Jeff (age 51)
Nutley, New Jersey, USA
A:

Those reflective surfaces aren't perfect. Say that you have extraordinarily good ones, reflecting 99.9% of the light.(Ordinary mirrors would be about 100 times as absorbing as that.) After a few thousand bounces, almost all the light will be gone. If the room has typical dimensions of 3 meters, light bounces off the surfaces about 108 times per second. So in  a few microseconds, the light is almost all absorbed.

Mike W.


(published on 12/19/2016)

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