We have seen in the last module (Relativity and
Electrodynamics) that the equation of motion for a particle with
charge e in an electromagnetic field is given by the Lorentz force
law
(1)
This of course looks the same as the non-relativistic version,
however here is the relativistic 3-momentum (the
space-components of the 4-momentum)
and 
fields
is the Lorentz boost.