Distance from the object to objective lens and focal length

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SUMMARY

The discussion focuses on calculating the working distance from an object to a medium-power objective lens in a microscope with a focal length of 3.70 mm, which produces a lateral magnification of -42.5. The formula used is m = -di/fobjective, where 'm' represents magnification, 'di' is the image distance, and 'fobjective' is the focal length. Participants suggest using a ray diagram to better understand the derivation of the formula and to accurately determine the working distance.

PREREQUISITES
  • Understanding of optical principles, specifically magnification and focal length.
  • Familiarity with ray diagrams in optics.
  • Knowledge of basic microscope components and their functions.
  • Ability to manipulate and rearrange equations in optics.
NEXT STEPS
  • Study the derivation of the magnification formula m = -di/fobjective in detail.
  • Learn how to construct and interpret ray diagrams for optical systems.
  • Research the relationship between working distance and focal length in microscopy.
  • Explore the calculation of eyepiece focal lengths for desired overall magnification.
USEFUL FOR

This discussion is beneficial for students studying optics, particularly those in biology or physics courses, as well as educators teaching microscopy principles and optical calculations.

bubothedog
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Homework Statement


1) The medium-power objective lens in a laboratory microscope has a focal length fobjective = 3.70mm . If this lens produces a lateral magnification of -42.5, what is its "working distance"; that is, what is the distance from the object to the objective lens?
2)
What is the focal length of an eyepiece lens that will provide an overall magnification of -130? Assume student's near-point distance is N = 25 cm

Homework Equations



m=-di/fobjective

The Attempt at a Solution


I tried using that formula to solve for this distance for object but it doesn't work out. I got that formula from a book where they assume that do is approx to be fobjective. Tbh, I don't quite understand how to get this "working distance". Anyone can help?
 
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Have you drawn a ray diagram? It should help you understand how "m=-di/fobjective" can be derived and thus, help you understand the question.
 

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