  It is a well-known fact that light rays do not follow the null geodesics of
the space-time in nonlinear electrodynamics; instead, they follow the null
geodesics of the so-called effective space-time. Taking this into account, in
this paper, we aim to discuss the possibility of distinguishing the type of
charge with which the black hole is endowed, via the motion of light rays. The
results show that, for any black hole being a charged solution of the field
equations of general relativity coupled to the nonlinear electrodynamics, one
cannot distinguish the two types of charge (magnetic or electric) through the
motion of light rays around it.
