Calculate the focal length of a planoconvex lens?

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SUMMARY

The focal length of a planoconvex lens can be calculated using the lens formula 1/f = 1/v + 1/u. In this discussion, the object distance (u) is 2.5 cm, and the image distance (v) is derived from the magnification of 2.5, resulting in v = 6.25 cm. Substituting these values into the lens formula yields a focal length (f) of 1.6 cm after inverting the final result. Understanding the definitions of u and v is crucial for accurate calculations.

PREREQUISITES
  • Understanding of the lens formula 1/f = 1/v + 1/u
  • Knowledge of magnification concepts in optics
  • Familiarity with object distance (u) and image distance (v) definitions
  • Basic algebra skills for manipulating equations
NEXT STEPS
  • Study the principles of geometric optics and lens behavior
  • Learn about different types of lenses and their focal lengths
  • Explore real-world applications of lenses in optical devices
  • Investigate the impact of lens curvature on focal length
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Students studying optics, physics educators, and anyone interested in understanding lens calculations and their applications in real-world scenarios.

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Homework Statement



Calculate the focal length of a planoconvex lens that produces a real image 2.5 times as big as the object if the object is 2.5 cm from the lens?

Homework Equations



The only one I can think of is 1/f = 1/v + 1/u

The Attempt at a Solution


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My 'attempt' is 1/f = 1/62.5 + 1/25 = 0.056 but this just seems totally wrong.

Had a whirl at it, but cannot produce an answer, any help would be really appreciated!
 
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givemeknowledge said:
The only one I can think of is 1/f = 1/v + 1/u

I'm not familiar with u and v in these equations. I think my class labels them differently. What do they represent here?
 
You have to invert the answer to get f :)
 

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