Q. The plane faces of two identical plano-convex lenses each having focal length of $40\ cm$ are pressed against each other to form a usual convex lens. The distance from this lens, at which an object must be placed to obtain a real, inverted image with magnification one is
A) $80\ cm$
B) $40\ cm$
C) $20\ cm$
D) $162\ cm$
Explanation
(b) To obtain, an inverted and equal size image, object must be paced at a distance of $2f$ from lens, $i.e.\ 40\ cm$ in this case
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Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.