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Introduction
In an earlier article, we examined a magnet falling through a solenoid. We argued that the point dipole model can account for the basic features of the induced emf across the solenoid ends. Here, we extend the model to a magnet falling through a conducting pipe along its axis.
With the falling dipole moment oriented along the vertical-axis, the electric field is tangent to circles centered on the axis. The induced emf around a closed loop of radius is . There is a similarity and a difference between a solenoid and a conducting pipe placed in that space. The similarity is in their modeling as a stack of conducting rings. The difference is in the conceptual connection of the constituent rings. In the solenoid, the rings are in series and the overall emf across them is of interest. In the pipe...
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