1. Not finding help here? Sign up for a free 30min 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!

Determining the object distance from a magnifying glass

  1. Apr 15, 2014 #1
    1. The problem statement, all variables and given/known data
    A magnifying glass has a focal length of 8.0 cm. How close to an object do you need to place the magnifying glass so that the distance between the image and the magnifying glass is the same as the focal length? What type of image is this and what is its magnification?




    2. Relevant equations

    I am thinking that you use the Lens/Mirror equation

    1/focal length = 1/object distance + 1/image distance


    3. The attempt at a solution
    I am unsure of how to do this because I am after object distance. So what I did was 1/object distance = 1/focal length - 1/image distance. But when I do that they just cancel because focal length and image distance are supposed to be the same thing. Once I figure that out I can handle the image type and magnification.

    Thanks, ChuggZ
     
  2. jcsd
  3. Apr 15, 2014 #2

    PhysicoRaj

    User Avatar
    Gold Member

    What you have done is right. Don't stop just because they cancel out, continue and solve for what you want.
     
  4. Apr 16, 2014 #3

    ehild

    User Avatar
    Homework Helper
    Gold Member

    The image can appear at both sides of the lens. You know only the distance of the image from the lens, but the sign of the image distance can be both positive and negative.

    ehild
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Determining the object distance from a magnifying glass
Loading...