Dependence on the point of impact
From the list of questions mentioned above, two remain to be analyzed: i) will there be areas in which the rays emerging from the drop are concentrated with greater intensity and, if they exist, will they depend on the color? ii) how can we apply the conclusions to the real situation that interests us: that of the sun's rays, which are a mixture of rays of different colors?
Starting with i), a close observation of the previous figure seems to suggest that, for each of the colors, there is a greater concentration of rays \(C_{3}\) and \(C_{4}\) at the ends of the direction arcs. Let us analyze the variations in the directions of refracted rays (of classes \(C_{2}\), \(C_{3}\) and \(C_{4}\)) as a function of the point of impact on the drop, to see if we can notice something that confirms this observation.
The following figure shows, for two incident ray beams, one in the intermediate zone and the other close to one of the extreme directions, the paths of the rays \(C_{ 3}\) in the drop, the final directions, the corresponding zones in the graph of the function that associates the direction of the ray \(C_{ 3}\) to each impact parameter, and a zoom close to one of the extreme directions.
The following interactive application allows to analyze the variations in the refracted ray directions (of classes \(C_{2}\), \(C_{3}\) and \(C_{4}\)) as a function of the point of impact on the drop and of the color of the incident ray.