How is magnification for the objective lens = L/fo

Where fo is the focal length of the objective

And L is tube length 

Asked by prakriti12oct | 18th Feb, 2020, 02:11: AM

Expert Answer:

 
Magnification of objective lens = A'B' / AB  = h' / h  ( see figure )
 
where h is size of object , h' is size of image
 
we have tanβ = h'/L = fo / h  ( see figure )
 
where fo is focal length of objective lens and  L is distance between second focal point of objective lens
and first focal point of eyepiece as shown in figure
 
hence h'/h = fo / L  
 
Hence magnification of objective lens = fo / L

Answered by Thiyagarajan K | 18th Feb, 2020, 07:53: AM

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