Physics Help Forum Confusion with angular magnification

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 Jul 8th 2018, 09:27 AM #1 Junior Member   Join Date: May 2017 Location: Sri Lanka Posts: 27 Confusion with angular magnification The angular magnification defined as, angle subtended by image of object /angle subtended by object when 25 cm from the naked eye Consider this. An object is placing 50cm in front of a convex lens which has a focus length of 100cm. So the image will create 100cm in front of the lens. If we consider the angular magnification, angle subtended by image of object /angle subtended by object when 25 cm from the naked eye =(h/100)/(H/25) [h=image height H=object height] My question is this. According to the above definition this should be correct. But, according to my feelings, I feel that the meaning of the angular magnification of the lens is, angle subtended by image of object /angle subtended by object at its own placement That means according to above example, =(h/100)/(H/50) (That because according to the word 'angular magnification' I feel it is relative to its normal location angle, that is not 25cm, it is regarding to the place which is keeping the object) What is the wrong in my thinking. Why do the definition limited the object to the least distance of eye can clearly see? Why isn't it depend on the place which the object keeps...... I am confuse with them. Last edited by osalselaka; Jul 8th 2018 at 09:54 AM. Reason: explained more
 Jul 8th 2018, 11:48 AM #2 Senior Member   Join Date: Apr 2015 Location: Somerset, England Posts: 1,029 Read this. I cannot put it more clearly. Note that 250mm is just a standard distance for comparison of the power of lenses. The magnification does indeed depend upon the object distance. Did you note whether such an image is real or virtual? Attached Thumbnails     Last edited by studiot; Jul 8th 2018 at 02:42 PM.

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