  The effect of the electrodynamic forces on a charged particle in a
propagating plane electromagnetic wave is investigated. First it is pointed out
that for constant fields fulfilling the radiation condition there will be an
acceleration in the direction of the Poynting vector. When oscillating fields
are considered the Lorentz force on the particle only causes a drift, with
constant average velocity, in the direction of propagation of the wave, i.e.\
the direction of the Poynting vector. Finally, when the radiative reaction
(radiation damping) force is added the result is again an acceleration in the
direction of wave propagation. PACS classification numbers: 03.50.De, 41.60.-m,
41.75.Jv
