Hi friends, Please help me in answering this problem The problem is as follows, https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-prn1/s480x480/11130_2937865262994_1085043361_n.jpg Well, Friends when the lower mirror would be at position 'A', which is moving in the upward direction, the img of the source 'S' will be at position (I') as shown in the figure below. And and after some time when the mirror will be at position 'B' the same ray will make the img of the source and the new position (I'). https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-ash3/60754_2937792661179_1384286388_n.jpg Hence the answer of the question should be option (A). But in the book the answer of the problem is given options (B) & (D) Please friends help me in this problem. Thank you very much in advance.