SOLUTION: Telephoto lens. Use the formula 1/F=1/O + 1/I to find the image distance I for an object that is 2,000,000 mm from 250 mm telephoto lens.

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Question 58715: Telephoto lens. Use the formula 1/F=1/O + 1/I to find the image distance I for an object that is 2,000,000 mm from 250 mm telephoto lens.
Answer by funmath(2933) About Me  (Show Source):
You can put this solution on YOUR website!
Telephoto lens. Use the formula 1/F=1/O + 1/I to find the image distance I for an object that is 2,000,000 mm from 250 mm telephoto lens.
F=250 mm
0=2,000,000
It's often easier to solve the formula for the value you want and then plug in your values.
1%2FF=1%2FO%2B1%2FI
1%2FF-1%2FO=-1%2FO%2B1%2FO%2B1%2FI
1%2FF-1%2FO=1%2FI
O%2FFO-F%2FFO=1%2FI
%28O-F%29%2FFO=1%2FI
%28%28O-F%29%2FFO%29%5E%28-1%29=%281%2FI%29%5E-1
FO%2F%28O-F%29=I%2F1
I=FO%2F%28O-F%29
Plug in your values:
I=%28250%29%282000000%29%2F%282000000-250%29
I=%28500000000%2F1999750%29
I=250.0312539
I=250 mm after you round off to sig. figs.
:
Now, if you think about it, your ariginal formula was:
1%2FF=1%2FO%2B1%2FI 2,000,000 is aproaching infinity, so 1/2,000,000 is very close to 0.
1%2FF=0%2B1%2FI
F=I which is what we ended up with.
Happy Calculating!!!