Observe the image carefully. A girl is standing outdoors on a sunny day, holding a shiny surface (likely a mirror) and reflecting sunlight onto a wall.

Now, answer the following questions :
(a) What optical phenomenon is being demonstrated in this picture? Explain the principle involved using a suitable scientific term.
(b) If the girl tilts the mirror slightly, what will happen to the spot of light on the wall? Justify your answer with the law or rule that governs the change in the path of light.