1. The problem statement, all variables and given/known data You put a point source of light (S) a distance (d) in front of screen (A). How is the light intensity at the center of the screen changed if you put a completely reflecting mirror (M) a distance (d) behind the source? M-----d-----S-----d-----A 2. Relevant equations I=Power/Area ?? 3. The attempt at a solution The answer it is giving in the book is 10/9 of the original intensity but i have no clue at all how to get this.