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!

Homework Help: Optics - Lens

  1. Mar 19, 2014 #1
    1. The problem statement, all variables and given/known data

    Two converging lenses of the same focal length f are separated by distance 2f. The axis of the second lens is inclined at angle θ = 60º with respect to the axis of the first lens. A parallel paraxial beam of light is incident from left side of the lens. Then:

    fmuerc.jpg

    (A) Final image after all possible refraction will formed at optical centre of first lens
    (B) Final image after all possible refraction will formed at optical centre of second lens
    (C) Final image after all possible refraction will formed at distance f from second lens
    (D) Final image after all possible refraction will formed at distance f from first lens


    2. Relevant equations

    f = p.p'/p+p'

    3. The attempt at a solution

    Here the solution:
    6iwk7t.jpg
    But, I don't agree with this line:

    f/x = cos 60, but I think the correct is x/f = cos 60, so x = f/2. But the answer is 2f. Anyone could see if i'm wrong ?
     
  2. jcsd
  3. Mar 20, 2014 #2

    ehild

    User Avatar
    Homework Helper

    You are right, the first image is at f/2 distance from the second lens.

    ehild
     
  4. Mar 20, 2014 #3

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Check by tracing out a ray diagram - the image from the first lens is the object for the second.
    You can also see how your course notes tell you to treat the situation when a lens is tilted.
     
  5. Mar 20, 2014 #4
    Thanks man.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted