  The impacts of dust density inhomogeneity and dust size distribution (DSD) on
linear dust acoustic (DA) wave propagation have been investigated theoretically
in an inhomogeneous unmagnetized dusty plasma having powerlaw DSD. Two
different types of wave modes, viz. slow and fast mode, are found to propagate
in this inhomogeneous medium. It is shown that the linear dispersion
characteristics of the DA waves are substantially affected by the DSD and
density inhomogeneity. Also, it is found that the phase velocity increases with
increasing dust density.
