  Charges on the dust grains immersed in a plasma vary in time. We follow the
hydrodynamic approach to obtain dispersion relations for some low frequency
electrostatic modes, taking into account charge fluctuation on the dust. We
have used the description of the one dimensional fully electromagnetic particle
code. There exists one spatial dimension and three velocity components. This is
usually referred to as a model. Our analysis shows that the presence of the
dust grains causes different effects in different frequency regimes.
