s*******y
发帖数: 105 | 1 A straight pipe with the opening cross section S is filled with
dust. The number of dust particles is N>>1, cross section of
each particle is s, and the total cross-section Ns=S. The
particles are blocking light coming through the pipe, but not
completely, because their shadows overlap due to random positions.
What is the pipe's light transmission coefficient?
有个解法是：
If the pipe is long enough, then only parrllel light paths can possibly
transmit through the pipe. Therefore, the | t*******e
发帖数: 172 | 2 each time, the prob of a point not covered by a dust is 1-1/N. which means
that after N times the prob of a point not covered by N dust is (1-1/N)^{N}.
as N -> infinite. it is 1/e. |
|
