(i) Draw a ray diagram to show the formation of image by a concave lens when an object is placed in front of it.
(ii) In the above diagram mark the object-distance (u) and the image distance (v) with their proper signs (+ve or -ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the concave lens in this case.
(iii) Find the nature and power of a lens which forms a real and inverted image of magnification -1 at a distance of 40 cm from its optical centre.
