Many problems of electric field strength on a boundary between two media require college-level mathematical analysis. However, when the boundary between media is represented by a sphere or a flat plane, these types of problems can be solved algebraically, placing them within reach of high school students. This article presents a solution analysis of the typical problems utilizing the well-known principle of superposition, which allows simple and precise calculations of electric field parameters. (Contains 10 figures and 1 footnote.)