Okay, I know that the brightness of light dims by 1 / r^2. I just need a little help about brightness and so forth. What exactly is the unit of brightness ? Also, when using 1 / r^2 Say I am 5 meters away from a light bulb and find the brightness, then I step back 47 meters. Would I just find the brightness by 47 - 5 = 42. Then take 1 / 42^2 = 1/1764 So, then if I move 42 meters away it would be 1/1764 less bright. Then it would be from my original position?