1. The intensity of illumination is inversely proportional to the square of the distance to the light source. It is modelled by the formula I = %, where [ is the intensity, in lux; d is the distance, in metres, from the source; and k is a constant. When the distance from a certain light source is 50 m, the intensity is 6 lux. a) Skerch a graph of this relation. b) Describe what happens to the light intensity as the distance becomes greater. ) Comment on the model for values of 4 close to 0