In sense of the phenomena of mirror effects, the behavior of electrons inside the chamber of scanning electron microscope (SEM) investigated. Indeed, a simplified geometrical explanation for the behavior of incident electrons introduced. The presented description is mainly concerns with simple trigonometric functions. However, the synthesis of these functions provide a tool which can be used to trace electron as it leaves the column diaphragm until it reaches the detectors. Accordingly, the position of landing electrons throughout its travel being determinable in terms of the sample potential the operation variables. Results have shown that introduced approach could commendably use to simulate behavior of electrons inside the chamber of SEM.