(vii) A convex lens has focal length 12 cm with an object at a distance of 20 cm in front of the lens. He obtains a blurred image on the screen placed at a distance of 23 cm in front of the lens. In order to obtain the clear image, he has to move the screen (a) towards the lens . (b) away from the lens. (c) to a position very far away from the lens. (d) either towards or away from the lens.
