How can we decided the power of lenses is positive or negative ? Is the image distance for a convex lens is positive ?

Asked by Prajyot Tugaonkar | 11th Jan, 2014, 08:35: PM

Expert Answer:

Power of a lens is inverse of its focal length. The focal length of convex lens is positive, so its power is also positive. The focal length of concave lens is negative, so its power is also negative.
The image distance for a convex lens is positive for real image and negative for virtual image.

Answered by  | 12th Jan, 2014, 08:29: PM

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