question_answer

Answer the following questions : (a) A man holding a lighted candle in front of a thick glass mirror and viewing it obliquely sees a number of images of the candle. What is the origin of these multiple images? (b) You read a newspaper because of the light that it reflects. Then why do you not see even a faint image of yourself in the newspaper? (c) The wall of a room is covered with a perfect plane mirror, and two movie films are made, one recording the movement of a man and the other of his mirror image From viewing the films later, can an outsider tell which is the mirror image film?                      

Answer:

                (a) The front surface of a thick glass mirror is both reflecting and refracting. The back surface is silvered and acts as a mirror. Images are formed by thick glass mirror due to (i) reflection at front surface (ii) reflection at the back surface, the brightest image (iii) multiple reflections within the thickness of glass. Hence a number of images are formed. All these images lie on the normal from the object to the mirror, and shown m Fig.                 (b) We can see an image, if it is caused by regular reflection. In case of a newspaper, the in homogeneities of the surface cause diffused reflections. So the incident parallel beam is scattered in all directions. Hence no image is seen. (c) Nature exhibits left right symmetry i.e., physical laws are the same for an object and its mirror image. Therefore an outsider, cannot distinguish between the two films. However, the distinction can be made if there is any initial asymmetric information. For example, if it is known that the man is a left-hander, then his image will appear to be a right-hander. And from watching the two films one can tell which is the mirror image film.