In this paper we examine two models for a current-carrying wire in special relativity. The first model assumes an infinitely long wire and does not specify the source or return path for the current. This model is simple and easy to analyze, so it is often used in introductory textbooks to show the significance of special relativity for electromagnetism. The second model is a coaxial line with a battery at one end and a short circuit at the other. The center conductor of the line represents the wire of interest, and the outer conductor forms the return path for the current. The analysis for this model is more involved than that of the first model, but it provides information not available from that model. This new information answers questions a student might have when first encountering the simpler model.

中文翻译：

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狭义相对论中载流线的另一种观察

在本文中，我们研究了狭义相对论中载流导线的两种模型。第一个模型假设电线无限长，并且没有指定电流的源或返回路径。该模型简单、易于分析，因此常被用在入门教材中，以展示狭义相对论对于电磁学的意义。第二种模型是一根同轴线，一端有电池，另一端有短路。线路的中心导体代表感兴趣的电线，外部导体形成电流的返回路径。该模型的分析比第一个模型更复杂，但它提供了该模型无法提供的信息。这些新信息回答了学生第一次遇到更简单的模型时可能遇到的问题。