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: Image Projection

  1. Feb 25, 2006 #1
    "A 35 mm slide (picture actually 24*36 mm) is to be projected on a screen 1.8*2.7 m placed 9 m from the projector. What focal length lens should be used if the imageis to cover the screen?"

    I was trying to do this problem using the formula (1/do)+(1/di)=(1/f), but hten i realized i dont have the object distance, so what formula can i use?
  2. jcsd
  3. Feb 25, 2006 #2
    There is a formula for magnification? Try if you remember.
  4. Feb 25, 2006 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Try http://hyperphysics.phy-astr.gsu.edu/ this usually gives good information. I believe you assume that object distance, which in this case is the slide, is zero.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook