【摘要】 坡印亭定理是电磁场与电磁波教学中的重要内容,涉及很多重要的物理概念,但教学过程容易忽视物理背景的引入,变成数学推导,导致学生对电磁场能量守恒与转化定律理解的偏差和物理概念的忽视。本文以坡印亭定理的教学为例,就坡印亭定理与电磁场能量守恒与转化定律的关系进行分析,导出了不同媒质中电磁场能量密度的表示式,分析其物理意义,并对坡印亭定理教学中容易出现的问题进行了讨论。更多还原

【Abstract】 Poynting theorem is an essential to teach electromagnetic field and wave. After introducing the background of energy conservation and conversion law, we write the equation of energy conservation and conversion law of electromagnetic field, and deduce the equation of Poynting theorem. Based on the formal consistency between the two equations, we interpret physical meanings of terms in the equation of Poynting theorem, and obtain the expression of power-flow density and energy density of electromagnetic field in various medium. We also explain physical concepts associated energy conservation and conversion law of electromagnetic field, and discuss how to teach these concepts.更多还原