Comment on: The electromagnetic field of a circular parallel plate capacitor excited by an AC current and AC voltage supply [Physica Scripta (2024) 99 125539]

In a recent paper [Physica Scripta (2024) 99 125539] Shejiao Han et al studied the electromagnetic field of an ideal circular parallel plate capacitor. Not only the authors have used a wrong approach to establish the boundary conditions of the problem but also claimed that the electromagnetic field solution depends on the type of AC source that feeds the capacitor. The approach followed by the authors consisted in dividing the geometry into two regions, the lead wire subspace and the dielectric subspace, boundary conditions being set by matching the fields of those subspaces at a particular point of the interface. The approach is inadequate because the problem involves not two but three subspaces, the plate subspace where surface currents flow is missing in the analysis. Consequently, the published results for the capacitor’s electromagnetic field are incorrect.