Why Is My Calculation of Lens Object Distance Incorrect?

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SUMMARY

The discussion focuses on calculating the object distance (do) in a lens system where a real image is formed. The object is placed to the left of the lens, and the image is inverted and half the size of the object, with a total distance of 102.0 cm between the object and image. The correct formula to use is the magnification equation, m = -di/do, and the relationship m = -q/p, where q is the image distance and p is the object distance. The participant initially misinterpreted the terms, leading to incorrect calculations.

PREREQUISITES
  • Understanding of lens formulas, specifically magnification equations.
  • Familiarity with the concepts of object distance (do) and image distance (di).
  • Basic knowledge of optics, particularly real images and their properties.
  • Ability to manipulate algebraic equations to solve for unknowns.
NEXT STEPS
  • Study the lens formula: 1/f = 1/do + 1/di for thin lenses.
  • Learn about the sign conventions in optics for object and image distances.
  • Explore practical applications of lens calculations in real-world scenarios.
  • Investigate the effects of different lens types (convex vs. concave) on image formation.
USEFUL FOR

Students studying optics, physics educators, and anyone involved in optical engineering or lens design will benefit from this discussion.

luap12
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1.An object is placed to the left of a lens, and a real image is formed to the right of the lens. The image is inverted relative to the object and is one-half the size of the object. The distance between the object and the image is 102.0 cm.

(a1) How far from the lens is the object?



2.m=-(di/do)



3. with the equation above I thought it was just -1/2=120/do and solving for do gives -204 cm, but this answer is wrong, and so is 204. I know that m is negative because the image is inverted. Not sure if my logic is right or not, we haven't covered this yet in class but it is still on the homework.
 
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M = -q/p, in which q is the distance from the lens to the image and p is the distance from the lens to the object. The 102cm given is the distance between the object and image.
 
That worked, thanks. I had the wrong idea of what the terms actually meant.
 

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