Calculating Angular Magnification: f=10cm, i=25cm

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SUMMARY

The discussion centers on calculating angular magnification for a lens with a focal length (f) of 10 cm and an image distance (i) of 25 cm. The angular magnification (Ang mag) is derived using the formula Ang mag = theta_image/theta_object. The final calculated angular magnification is 1.335, achieved by determining the angles using the arctangent function for the object and image distances. A key correction noted is the importance of using the magnification formula M = -(image distance)/(object distance) for accurate results.

PREREQUISITES
  • Understanding of lens formulas, specifically the thin lens equation.
  • Familiarity with trigonometric functions, particularly the arctangent function.
  • Knowledge of angular magnification concepts in optics.
  • Ability to manipulate ratios and perform basic algebraic calculations.
NEXT STEPS
  • Study the thin lens equation and its applications in optics.
  • Learn about the properties of angular magnification in different optical systems.
  • Explore the relationship between object distance, image distance, and magnification.
  • Investigate the effects of varying focal lengths on image formation and magnification.
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rootX
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Homework Statement


f = 10 cm
i = 25 cm
Find angular magnification of lens


Homework Equations



Ang mag = theta_image/theta_object

The Attempt at a Solution



I found p to be 16.67
using 1/p+1/25=1/10

and I am not sure about the next step.
theta_0 = atan (16.67/25)
theta_f = atan (25/25)

and found thetas, and divided them to get 0.785/0.588=1.335 as my final answer.
 
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rootX said:

Homework Equations



Ang mag = theta_image/theta_object

The Attempt at a Solution



I found p to be 16.67
using 1/p+1/25=1/10

I agree with your object distance...

and I am not sure about the next step.
theta_0 = atan (16.67/25)
theta_f = atan (25/25)

But the angular size of an object or image is the tangent of its linear size to its distance from the observer. (You don't want to take ratios of p/f and f/f.) You have no information about the object itself or the size of the image. I think you'll want to use the ratio

magnification M = -(image distance)/(object distance) .
 

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