We study a static, spherically symmetric wormhole model whose metric coincides with that of the so-called Ellis wormhole but the material source of gravity consists of a perfect fluid with negative density and a source-free radial electric or magnetic field. For a certain class of fluid equations of state, it has been shown that this wormhole model is linearly stable under both spherically symmetric perturbations and axial perturbations of arbitrary multipolarity. A similar behavior is predicted for polar nonspherical perturbations. It thus seems to be the first example of a stable wormhole model in the framework of general relativity (at least without invoking phantom thin shells as wormhole sources).Comment: 6 pages, no figure

We consider the self-potential and the self-force for an electrically charged particle at rest in the massive wormhole space-time. We develop general approach for the renormalization of electromagnetic field of such particle in the static space-times and apply it to the space-time of wormhole the metric of which is a solution to the Einstein-scalar field equations in the case of a phantom massless scalar field. The self-force is found in manifest form; it is an attractive force. We discuss the peculiarities due to the parameter of the wormhole mass.

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The free fall of electric charges and dipoles, radial and freely falling into the Schwarzschild black hole event horizon, was considered. Inverse effect of electromagnetic fields on the black hole is neglected. Dipole was considered as a point particle, so the deformation associated with exposure by tidal forces are neglected.According to the theorem, "the lack of hair" of black holes, multipole magnetic fields must be fully emitted by multipole fall into a black hole. The spectrum of electromagnetic radiation power for these multipoles (monopole and dipole) was found.Differences were found in the spectra for different orientations of the falling dipole.A general method has been developed to find radiated electromagnetic multipole fields for the free falling multipoles into a black hole (including higher order multipoles quadrupoles, etc.). The electromagnetic spectrum can be compared with observational data from stellar mass and smaller black holes.

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