Geometrical OpticsHard
Question
When the object is at distance u1 and u2 image formed by the same lens real and virtual respectively and of the same size. Then focal length of the lens is :
Options
A.
B.
C.
D.
Solution
m1 = 
m2 = 
; 
= - 1
⇒ u2 - f = - (u1 - f) ⇒ u1 + u2 = 2f
⇒ f =
m2 = ; = - 1⇒ u2 - f = - (u1 - f) ⇒ u1 + u2 = 2f
⇒ f =
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