The Problem of Non-linearity: An Engineering Students’ Misconception

Abstract

Linearization of non-linear physical processes is a standard approach for analyzing various non-linear systems. It is widely used in different engineering disciplines. It is known that school students are inclined to apply linear or proportional models in mathematical and physical problem solving. However, engineering students have difficulties with linearization and do not always apply the method correctly. A long pedagogical practice of more than 30 years in the field of electricity and electronics higher education have brought the authors to the assumption that the students have a misconception of non-linearity, which prevents them from understanding of the concept correctly. Students' difficulties with linearization are expressed in the Analog Electronics course, where the students first encounter non-linear components-diodes. Electrical engineering students learn Analog Electronics after the Electricity and Electrical Circuits course, during which they mostly deal with linear interpretations of basic electrical components – resistors, capacitors and coils. At the very beginning of diode learning the students look for a simple linear dependency between current and voltage, like Ohm law. Afterwards, they misunderstand that they need to choose an appropriate linear model according to different circuit conditions, and to use it. A qualitative research methodology was applied. 12 open interviews with the students were carried out. Two main problems were found: 1) part of the students do not perceive why different circuit conditions demand different linear models; 2) while solving the problem, some students cannot choose the correct model and determine the suitability of the results to the given conditions. The study can help the engineering educators to be aware of students' misunderstanding of non-linearity and find pedagogical ways to overcome it.