Question 141837: The focal length f for a camera lens is related to the object distance 0 and the image distance i by the formula
l = l + l
- - -
f = 0 + i
f = 250 mm and 0 = 2,000,000
l = l + l
-------------------------
250 = 2,000,000 + i
Use the formula to findthe image distance i for an object that is 2,000,000 mm from a 250-mm telephoto lens.
Please help. I'm not sure if I have this set up correctly or how to proceed. Thank you, Anne
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! l l 1
--- = ---------- + --------
250 2,000,000 i
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If your equation is correct you can solve for "i":
1/i = [1/250] -[1/2mil]
1/i = [2mil - 250]/[500 mil]
Inverting both sides you get:
i = [500 mil]/[2mil-250]
i = [500 mil] / [1.5mil]
i = 333 1/3 million
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Cheers,
Stan H.
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