1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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!

Object Distance from Lens

  1. Apr 12, 2009 #1
    1. The problem statement, all variables and given/known data
    An object is in front of a lens with a focal length of -15cm. An image ½ the side of the object is formed. How far is the object from the lens?

    2. Relevant equations
    m - magnification
    q - distance from image
    p - distance from object
    f - focal length

    m = -q/p
    1/p + 1/q = 1/f

    3. The attempt at a solution
    m = -q/p so q = -(1/2)p

    1/p + 1/q = 1/f
    1/p + 1/(-1/2p) = 1/-15cm
    -1/p = 1/-15cm
    p = 15 cm
  2. jcsd
  3. Apr 12, 2009 #2


    User Avatar
    Homework Helper

    Your answer is correct.
  4. Apr 12, 2009 #3
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook