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!

Simple magnifier problem

  1. Aug 4, 2007 #1
    1. The problem statement, all variables and given/known data

    A boy scout starts a fire by using a lens from his eyeglasses to focus sunlight on kindling 5.2 cm from the lens. The boy scout has a near point of 15.2 cm. When the lens is used as a simple magnifier, give values for the following conditions. (Hint: Assume a "normal" eye.)
    (a) What is the maximum magnification that can be achieved

    (b) What is the magnification when the eye is relaxed

    2. Relevant equations
    1/p + 1/q = 1/f
    Mmax= 1+ 25cm/f

    3. The attempt at a solution
    I used p=+5.2 and q= -(15.2)-((1/2)5.2)=-17.8
    then 1/5.2 - 1/17.8 +1/f
    f= 7.34
    so, Mmax= 1+ 25/7.34= 4.406 but that is wrong?!?
    can anyone help?
  2. jcsd
  3. Aug 5, 2007 #2
    You have to put everything in meters... you're using cm... check your units...
  4. Aug 5, 2007 #3

    Doc Al

    User Avatar

    Staff: Mentor

    That last equation assumes a near point of 25cm, but you are given a different near point to use.

    (No problem using cm everywhere, as long as you are consistent.)
  5. Aug 5, 2007 #4
    So i used the same equation except for Mmax I used 1+ 15.2/7.346= 3.068 but still the answere is not right?
  6. Aug 5, 2007 #5
    Please help soon as I do not have much time left to solve this problem.
  7. Aug 6, 2007 #6

    Doc Al

    User Avatar

    Staff: Mentor

    What's the focal length of the lens?

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

Have something to add?

Similar Discussions: Simple magnifier problem
  1. Simple problem (Replies: 1)

  2. Simple Problem (Replies: 2)