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

Homework Help: Power Formula Problem

  1. Oct 7, 2006 #1
    (b) A car passes you on the highway and you notice the taillights of the car are 1.16 m apart. Assume that the pupils of your eyes have a diameter of 7.2 mm and index of refraction of 1.36. Given that the car is 14.1 km away when the taillights appear to merge into a single spot of light because of the effects of diffraction, what wavelength of light does the car emit from its taillights (what would the wavelength be in vacuum)?


    Okay so i know the formula is

    Theta = Index of Refraction* Wavelength / Distance

    How do i find the limiting angle of resolution in order to get the wavelenght
     
  2. jcsd
  3. Oct 7, 2006 #2

    Chi Meson

    User Avatar
    Science Advisor
    Homework Helper

    You want to be using the "Rayleigh Criterion". It's the one with the factor of 1.22 in it.
     
  4. Oct 8, 2006 #3
    ok but then Distance would be 13.5 Km and what is the limiting angle?

    (1.22)(X) / (7.2/1000) = ???
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook