Some parts of this window look brighter than others, even though the same amount of sunlight is striking all parts of the window. This is happening because some of the light striking the window is
OA. being absorbed.
ОВ.
causing the window to break.
OC. being changed into sound.
OD. being changed into electricity.

The illuminance of a surface varies inversely with the square of its distance from the light source. if the illuminance of a surface is 120 lumens per square meter when its distance from a certain light source is 6 meters, by how many meters should the distance of the surface from the source be increased to reduce its illuminance to 30 lumens per square meter?