A lens is used to produce a sharp image on a screen. When the right half of the lens is covered with on opaque material, how will image be affected? (i) The right half of the image will disappear. (ii) The left half of the image will disappear. (iii) The image size will become approximately \dfrac{1}{2} of the original size. (iv) The image brightness will become approximately \dfrac{1}{2} of the original brightness.