The plane faces of two identical planoconvex 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

Options

A. `80 cm`
B. `40 cm`
C. `20 cm`
D. `162 cm`

Answer

B

Explanation

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 .