Alight source emits 100 watts of visible radiation and is located at a distance of 1 meter from an observer. now suppose that the source is moved to a distance of 2 meters from the observer. which of the following statements correctly describes the change in the observed properties of the source?
a. the luminosity remains the same and the apparent brightness doubles.
b. the luminosity remains the same and the apparent brightness is reduced to 1/2.
c. the luminosity and the apparent brightness are reduced to 1/2.
d. the luminosity and the apparent brightness are reduced to 1/4.
e. the luminosity remains the same and the apparent brightness is reduced to 1/4.