On Friday, May 22, 2015 at 10:17:14 AM UTC-4, Scott Lurndal wrote:
Because it doesn't.
Visible light does not decrease with the inverse square rule.
Visible light from a point source decreases with the inverse square rule.
Visible light from a line source like a fluorescent tube decreases with a simple inverse, no square involved, rule. Until you get far enough away that a line source appears to be a point.
Visible light from a plane source doesn't decrease at all, until you get far enough away that it appears to be a point.
I'm reasonably sure that those seeming contradictions are because a given
point is receiving light from many areas of the large source. If one were to
measure the light fall off of each of those areas, the inverse square rule
would be true.
On Friday, May 22, 2015 at 1:37:48 PM UTC-4, dadiOH wrote:
It's called math.
Weren't you required to derive the inverse square rule at some point? It's a straightforward application of geometry.
But you always have to check your assumptions. Those assumptions require a point source, or a reasonable approximation.
There's another aspect I haven't seen mentioned. A moving magnetic
field induces a current in metal. A magnetic field powerful enough to
pull a nail might just heat it up enough to burn the wood it's in.
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