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: Find the object location with ray optics

  1. Nov 26, 2012 #1
    1. The problem statement, all variables and given/known data

    A 1.0-cm-tall object is placed 4.0cm from a diverging lens of focal length 6.0cm. Using both ray tracing and the thin lens formula, find the location and orientation of the image.

    2. Relevant equations
    -1/f = 1/so + 1/si
    m = -si/so = hi/ho

    3. The attempt at a solution
    -1/6cm = 1/4cm + 1/si
    si = -2.40 cm

    Okay so attached my ray tracing diagram.. (sorry for the crappy camera quality), but the point where the Si crosses the ho is supposed to be where the object distance is.. and i measured with my ruler that it is 0.4cm, not 2.4cm. What am I doing wrong in the drawing?

    Attached Files:

  2. jcsd
  3. Nov 26, 2012 #2


    User Avatar
    Homework Helper
    Gold Member
    2017 Award

    You haven't correctly drawn the ray that travels horizontally toward the lens. Hint: for this ray you'll need to use one of the focal points.
  4. Nov 27, 2012 #3
    Rays travelling parallel to the principal axis are refracted through the focal point of the lens.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook