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Eye focusing

by haxxorboi
Tags: focusing
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haxxorboi
#1
Nov13-08, 02:43 PM
P: 24
1. The problem statement, all variables and given/known data
Suppose the lens in a human eye has far focal length equal to f0 = 40.1 mm, for distant objects to be in focus.
A. An object K is 1.69 m from the lens. How much should the focal length change to focus on the object K?

B.What is the magnification ( = image size divided by object size) for the object K?


2. Relevant equations
1/di+1/do=1/f


3. The attempt at a solution
A. 1/1690+1/x=1/40.1
x=41.0746 mm
Thus, delta f = .9746 mm but that's wrong for some reason... but it's been a long week...

B. -f2/f1=M

Can someone help me out here?
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tiny-tim
#2
Nov13-08, 02:58 PM
Sci Advisor
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Quote Quote by haxxorboi View Post
1/1690+1/x=1/40.1

it's been a long week...
Hi haxxorboi!

Shouldn't the 1/x be on the other side?
haxxorboi
#3
Nov13-08, 04:15 PM
P: 24
*sigh* Yep, that'd be the issue... need either more sleep or more caffeine I guess...

Problem solved.

Thank you very much... I'm gonna go take a nap...


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