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Grade 12Wave Optics

Two convex lenses with focal length f are kept apart from each other at a distance of 3f. What will be the object distance so that the image formed by the lenses are real?

Profile image of Kallol Marjit
9 Years agoGrade 12
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1 Answer

Profile image of Vikas TU
9 Years ago
 
Central Length = f cm 
 
Picture Distance = v cm 
 
From the Lens recipe, 
 
1/v-1/u = 1/f 
 
1/u = (f-v)/fv 
 
u = fv/(f-v) 
 
As v = 3f 
 
u = 3f2/(- 2f) 
 
u = - 3f/2