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: Light: Geometric Optics

  1. Jul 27, 2011 #1
    1. The problem statement, all variables and given/known data
    A 35mm slide(picture size is actually 24 by 36 mm)is to be projected on a screen1.80m by 2.70 m placed 7.50m from the projector. What focal length lens should be used if the image is to cover the screen?

    2. Relevant equations

    the only equation i can think of is the lens equation which is (1/Do)+(1/Di)=1/f

    3. The attempt at a solution
    I have tried starting this problem numerous times and just have no clue how to start it
  2. jcsd
  3. Jul 27, 2011 #2


    User Avatar
    Homework Helper

    You need the formula for magnification, too.

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