The net force and net torque exerted by a uniform magnetic field on a rigid current-carrying loop are discussed in all introductory physics textbooks. A notable omission, however, is the discussion of the equilibrium of a deformable current-carrying loop in a uniform magnetic field. In the article, we present such an analysis for the simplest case of a quadrilateral current-carrying wireframe placed in a uniform magnetic field. We discuss the area-maximizing effect of the field on the frame and use the conditions of translational and rotational equilibrium to establish the ‘cyclicity’ of the latter as well as the uniformity of the magnitude of the contact forces acting at its joints.

所有介绍性物理教科书都讨论了均匀磁场对刚性载流回路施加的净力和净扭矩。然而，一个值得注意的遗漏是对均匀磁场中可变形载流回路平衡的讨论。在本文中，我们对放置在均匀磁场中的四边形载流线框的最简单情况进行了这样的分析。我们讨论了场对框架的面积最大化效应，并使用平移和旋转平衡条件来建立后者的“循环性”以及作用在其关节处的接触力大小的均匀性。