Light intensity (I) is proportional (a) to the inverse square of distance (d) of a subject from a light
source. The relationship in intensities for subjects at different distances from the same source can
be likewise seen as a ratio or proportional relationship.
I x
A proportional relationship can be mathematically expressed as follows for light intensity (I) in
lumens when a subject is at the light source.
Lumens at current distance
Lumens at origin or source
So, if a light intensity (I) is 516 lumens at the source and 4 lumens at a specific distance from the
source, what is that distance?
Round the value to the nearest tenth if necessary. You do not need to include a label for distance.
Only the number, rounded to the tenth, will be necessary.