  We investigate here the question raised in literature about the correct
expression for the electromagnetic field-momentum, especially when static
fields are involved. For this we examine a couple of simple but intriguing
cases. First we consider a system configuration in which electromagnetic field
momentum is present even though the system is static. We trace the
electromagnetic momentum to be present in the form of a continuous transport of
electromagnetic energy from one part of the system to another, without causing
any net change in the energy of the system. In a second case we show that the
electromagnetic momentum is nil irrespective of whether the charged system is
stationary or in motion, even though the electromagnetic energy is present
throughout. We demonstrate that the conventional formulation of electromagnetic
field-momentum describes the systems consistently without any real
contradictions. Here we also make exposition of a curiosity where
electromagnetic energy decreases when the charged system gains velocity. Then
we discuss the more general question that has been raised -- Are the
conventional formulas for energy-momentum of electromagnetic fields valid for
all cases? Or more specifically, in the case of so-called "bound fields," do we
need to change over to some modified definitions which have made their
appearance even in standard text books? We show that in all cases it is only
the conventional formulas which lead to results consistent with the rest of
physics, including the special theory of relativity, and that any proposed
modifications are thus superfluous.
