question_answer

The image of a candle is formed by a convex lens on a screen. The lower half of the lens is painted black to make it completely opaque. Draw the ray diagram to show the image formation. How will this image be different from the one obtained when the lens is not painted black?                     

Answer:

                When the lower half of the lens is painted black, the image formed is still of the same size as that with unpainted lens but it has now reduced intensity, as illustrated in Fig.