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: Question from an Extras Class.

  1. Jan 25, 2009 #1
    1. The problem statement, all variables and given/known data
    Got some work from my dad, but one question kinda stumped me.

    A short sighted person can view an object clearly only when it is between 11 cm and 19 cm from her eyes. Calculate:
    1. The Focal Length of the specatacles required to give her a near point of 25 cm.


    2. Relevant equations
    I don't know what equation to use here. I usually see questions about image and object distances and object distances using the 1/u+ 1/v= 1/f equation, I've never seen one like this.


    3. The attempt at a solution
    I just assumed, 1/.25 + 1/infinity = 1/f
    1/.25 + 0 = 1/f
    1/.25 = 1/f
    4 = 1/f
    f = 1/4
    f= .25
     
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted



Loading...