Analysis of Errors in Some Simplified Textbook Interpretations of Coil Coupling Coefficient

The coupling coefficient (k) between coils is a subject that is presented in textbooks of electricity, electric circuit analysis and electromagnetism. Some authors, however, make a partial or incomplete interpretation of the coupling coefficient, leading students to wrong results and misunderstandings. This paper presents the most common errors found in some textbooks, comparing them with the correct definition for coupling coefficient. A practical example is also provided.