Unit: Optics
Year: 1990 Question#: 98
Question: An object is placed 0.40 meter in front of a convex (converging) lens whose focal length is 0.30 meter. What is the image distance?
(1 ) 0.17 m
(2 ) 0.83 m
(3 ) 1.2 m
(4 ) 5.8 m
What is this question really asking?
Explanation by: Brian L
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Answer 1
0.17 m
INCORRECT
Use the equation:
When you solve for di, you do not get 0.17 m.
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Answer 2
0.83 m
INCORRECT
Use the equation:
When you solve for di, you do not get 0.83m. If you chose this answer, did you mistakenly calculate the inverse of the image distance?
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Answer 3
1.2 m
CORRECT
Solve for the image distance.
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5.8 m
INCORRECT
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What's this question really asking?
Can you use the thin-lens formula? The formula to know is:
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