A Student focussed the image of an object on a white screen using a converging lens. He noted down the positions of the object, screen and the lens on a scale as given below :
Position of a Object = 10.0 cm
Position of lens = 50.0 cm
Position of screen = 90.0 cm

i) Find the focal length of the converging lens .
ii) Find the position of the image if the object is shifted towards the lens at a position of 30.0 cm.
iii) State the nature of the image formed if the object is further shifted towards the lens .