(a) A lens forms a blurred image of an object on the screen as shown below:

What changes can you make to the following to form a sharp and in-focus image on the screen?
(i) object distance
(ii) focal length of the lens
(b) Sunita's ophthalmologist suggests her to use a lens of power -2 D to correct her vision.
(i) What type of lens should she use?
(ii) What should be the focal length of the lens?
(iii) An object is kept at 10 cm in front of the lens of power -2 D. Find the distance where the image is produced.