The teaching of basic circuits in early undergraduate physics courses is widespread and, to some extent, quite uniform. In most text books, the introduction of resistors, capacitors and inductors is followed by their assemblage into larger systems, together with mathematical calculations of charges and currents as functions of time. In this process, spatial features of circuits tend to be omitted. Here, we argue that this kind of omission is not "natural" but, rather, should be justified in terms of internal time-scales operating in the system, in the framework of the continuity equation. When space is brought back to the discussion of circuits, a number of important physical features, absent in most text books, emerge. Among them, one has: a spatial uniformity of currents, the existence of charges coating metallic surfaces, and the presence of charge distributions inside wires at the endings of resistors and coils. We believe that the discussion of these qualitative issues with students could foster a more mature and unified relationship with electromagnetism.

中文翻译：

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简单的电路没那么简单

早期本科物理课程中基本电路的教学是广泛的，并且在某种程度上是相当统一的。在大多数教科书中，在介绍电阻器、电容器和电感器之后，将它们组装到更大的系统中，以及电荷和电流作为时间函数的数学计算。在这个过程中，往往会忽略电路的空间特征。在这里，我们认为这种遗漏不是“自然的”，而是应该在连续性方程的框架内根据系统中运行的内部时间尺度来证明是合理的。当空间回到电路的讨论中时，就会出现许多在大多数教科书中没有的重要物理特征。其中，一个具有：电流的空间均匀性，金属表面涂层的存在，以及在电阻器和线圈末端的导线内部存在电荷分布。我们相信与学生讨论这些定性问题可以促进与电磁学的更成熟和统一的关系。