Spherical mirror;find focal length from given data?

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Homework Help Overview

The problem involves a concave mirror and the relationship between object distances and image sizes. The original poster seeks to find the focal length of the mirror given that images of the same size are formed at two different object distances.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to understand the implications of the given distances and the resulting image sizes, questioning the uniqueness of the image size at a specific point. Some participants clarify the interpretation of the problem, suggesting that the images formed at different object distances can still be the same size.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. There is a suggestion to consider the nature of virtual and real images, indicating a potential direction for further exploration.

Contextual Notes

Participants are navigating the complexities of image formation in mirrors, particularly regarding the conditions under which images of the same size can occur at different object distances. There is an indication of confusion regarding the relationship between object distance and image size.

vkash
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Homework Statement



When an object is at distance u1 and u2 from pole of concave mirror, images of same size are formed. Find the focal length of the mirror.

Homework Equations



1/v+1/u=1/f

The Attempt at a Solution



Can u please ray diagram for this question. I think their is only one point from which image of size of object form(that's 2f). But it is giving two points. So how to do it..
 
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I think you're misreading the question. It's not saying the image is the same size as the object. It's saying the image formed when the object is at u1 is the same size as the image formed when the object is at u2.
 
vela said:
I think you're misreading the question. It's not saying the image is the same size as the object. It's saying the image formed when the object is at u1 is the same size as the image formed when the object is at u2.

OK!
acha ji.()

but is it possible that two points have same size of image(for a fixed object). I think it will decrease as we take object from pole of the lens to infinity...

please tell me how to proceed..
 
Think virtual and real images.
 

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