Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Light being intercepted by dust

  1. Feb 15, 2006 #1
    There exists one dust grain of radius 0.1 micrometer per every 10^12 hydrogen atoms. Show that as light travels through a 1 cm layer of this comrpessed gas, only about 1% will be intercepted.

    Then show how thick a layer would be needed to block 1/e of the rays.

    I believe the density of the gas is about 2.7 x 10^19 atoms cm^-3

    Initially I thought that I should have used mean free path to solve this problem, but it was done with integrals. I'm assuming that this is an expected value problem, but I really have no idea how to set up the integrals. I believe that my variable must be the thickness of the gas however. Any hints?
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?