An object is placed in front of a convex lens of focal length . At what distance from the lens (in cm) is the image formed?
Answer and explanation
Correct answer: C. 60
- Step 1: Apply the thin lens formula with Cartesian conventions: and .
- Step 2: Rearrange to solve for reciprocal image distance: .
- Step 3: Calculating the difference and taking the reciprocal yields .
Answer
60.
Why not the others: 12 results from incorrectly adding reciprocals with a sign error (); 50 simply adds focal length and object distance (); 70 is an arithmetic error.
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