Study Some Ambiguities In Electromagnetics And Their CAI

It was found that physical instruction still had many kinds of problems though it had made a great progress, after we made an extensive and intensive research on the teaching of electromagnetics theory. Also, a large number of students felt that physics was too abstract and difficult to study. In order to pay more attention to that and find some measures to deal with such problems, we have made prepared to thrash out some ambiguities in electromagnetics and finish their CAI, and hoped that this study can become a kind of necessary complementarity and expanse for the curriculum teaching of electromagnetics. The main conclusions are as follows:First of all, applying the conception of flux lines to the theory of electromagnetic field makes abstract electrostatic field visible and intuitive. But due to the difficulties of the theoretical calculation and the limitation of the technique of image display, only some two-dimensional graphs of electromagnetic field of a planar set of point charges or symmetrically and uniformly charged bodies, which ignores the boundary effect, are introduced in the present electromagnetics teaching materials, which brings much incovenience for the acquaintance of the electrostatic field. In this paper, on the basis of existing tracing method and differential coefficient method, five new methods are put forward, superposing of infinitesimal element-tangent method, differential coefficient-tangent method and equation method, by taking advantage of fast calculating ability of the computer. Two-dimensional planar electrostatic field of complicated charged bodies are simulated successfully with these methods. The changing trend of electric field along a certain direction of a set of point charges are also given in this paper.Secondly, in Electromagnetic Wave domain, this about the polarization of electromagnetic waves is a difficult problem in teaching. In this paper, some basic concepts about polarization which are easily confused are demonstrated at first. Then, the definition about polarization, the synthesis and decomposition about Electromagnetic wave and the judgment about direction of polarization spin are introduced. In succession, with computer algebra system Maple, the dynamical plot of...