Induced electric field from a time‐dependent current

This note is an extension of the problem posed by Shakur,¹ and commented on by Gauthier,² which asks what induced electric field exists in the vicinity of a long straight wire carrying a current that increases linearly with time. While the problem appears to be elementary, it is in fact quite subtle—more for what it leaves out than what it includes. Here we pose and discuss a number of queries that might occur to someone not satisfied by Shakur’s ‘‘solution.’’