Magnetically uncharged, magnetic linear response of the vacuum filled with
arbitrarily combined constant electric and magnetic fields to an imposed static
electric charge is found within general nonlinear electrodynamics. When the
electric charge is point-like and external fields are parallel, the response
found may be interpreted as a field of two point-like magnetic charges of
opposite polarity in one point. Coefficients characterizing the magnetic
response and induced currents are specialized to Quantum Electrodynamics, where
the nonlinearity is taken as that determined by the Heisenberg-Euler effective
Lagrangian.Comment: The part dealing with magnetically charged responses is removed to be
a subject of another paper after revisio
