1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Optics -- caustic curve equation

  1. Feb 5, 2015 #1
    I went through this article:
    http://users.df.uba.ar/sgil/physics_paper_doc/papers_phys/ondas_optics/caustica1.pdf [Broken]
    But I think that when we do F=0, we are assuming the centre of the curve to be the origin and assuming the curve to be a circle, because only then will we be able to say that OP=ON (i.e. F=0)..either the article has some issues or I am interpreting it wrongly..please help..
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Feb 5, 2015 #2

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    What the author did is simply re-write r = R cos() sec() as r-R cos() sec() = 0. For technical reasons, it's often easier to work with equations like F = 0 instead of r = something, especially if you are talking about the geometry of surfaces.

    Caustics are really fun to study (IMO)- check this out:

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook