Interference typically focuses on two waves because it simplifies calculations and helps illustrate fundamental principles. While it is possible to analyze three or more waves, such as in multiple-slit interference, the basic approach often starts with two waves to establish the concept of maxima and minima. In practical applications, like homework problems, using two waves allows for easier calculations and clearer understanding. The distinction between "two waves" and "two sources" is important, as multiple waves can arise from each source, complicating the analysis. Ultimately, the choice of using two waves is a pedagogical strategy to introduce the concept of wave interference effectively.
