View Single Post
  #532 (permalink)  
Old 02-June-2005, 03:11 PM
Grey's Avatar
Grey Grey is online now
Order of Kilopi
 
Join Date: May 2003
Location: Michigan
Posts: 3,347
Default

Quote:
Originally Posted by lyndonashmore
Photon comes in from left to right and is absorbed, our middle electron is set into oscillation up and down between our two neighbours above and below it (whilst our electron recoils from left to right). We have done the recoil so let us look at the oscillations. According to Sylas the energy stored in this oscillation is equal to the energy of the photon which is 3.97e-19J. At the center of the oscillation all this energy takes the form of KE so what is the velocity of the electron? Answer is 9.5x10^5 m/s. Not a problem there is there since the random thermal energy gives the electron a velocity of 2.1x10^6m/s? Hardly an exceptional result is it? So there is no problem with the KE, let’s look at the PE.
Now, what's the upward momentum of this electron? And where did that momentum come from, since we've already used the entire momentum of the incoming photon? Or, more precisely, the incoming photon had no net upward momentum. So if the electron now has momentum in that direction, it must be balanced by an equal momentum downward, so that the total remains zero, just as it was before absorption. Again, you fail to show conservation of both energy and momentum.