petrushka.googol Posted November 11, 2013 Posted November 11, 2013 We all know Newtons refraction with a prism. We also know that light is essentially a beam of photons. In the light of this how do we explain refraction in terms of the incident photon beam. How "intelligent" is the photon in this regard? Please advise. Your views will be appreciated. Thanks in advance.
Strange Posted November 11, 2013 Posted November 11, 2013 Here is a series of lectures by Feynman explaining the mechanism. He was one of the main people who developed the theory (QED). http://vega.org.uk/video/subseries/8 (No intelligence required by the photon.)
Enthalpy Posted November 14, 2013 Posted November 14, 2013 Refraction, diffraction... are best explained in terms of waves. Photons were historically introduced to explain their absorption; they were not needed for the rest - and it's wise to forget their existence as long as they propagate, and remember them when they're absorbed.
JonG Posted November 14, 2013 Posted November 14, 2013 Refractive index is usually explained by considering the interaction between an electromagnetic wave and atoms in the refracting medium. The atoms are regarded as oscillating dipoles rather than atoms with discrete energy levels as described by quantum theory. In short, the treatment is classical rather than quantum mechanical. However, I have seen a treatment in which energy and momentum conservation is considered when photons incident on a refracting surface are split up into reflected and refracted categories and this does indicate that the behaviour of the photons is in accord with Fermat's principle. However, this approach does not, as far as I am aware, extend to explaining variation of refractive index with frequency - dispersion. There are many instances in which light is regarded as an electromagnetic wave rather than a stream of photons, and the reason for this is usually that the classical approach is simpler mathematically.
decraig Posted December 1, 2013 Posted December 1, 2013 (edited) You're reminding me of the good old days. With the advent of the calculus we were getting somewhere, then. Better than today's plodding misconstructions. But there were still disagreements that persist today. http://www.studyphysics.ca/newnotes/20/unit04_light/chp1719_light/lesson57.htm Who was right, Newton or Huygens? Edited December 1, 2013 by decraig
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now