If the image formed by a lens for all positions of an object placed in front of it is always erect and diminished, what is the nature of this lens ? Draw a ray diagram to justify your answer. If the numerical value of power of this lens is 10 D, what is its focal length in cartesian system ?

Explanation

`*` Convex Mirror
`*` Lebelled ray diagram for any position of object

Note: If arrows not markted, `1//2` mark be deducted