1.6.1 Force of gravity (Fg)

The dust particles which are under a gravitational force are proportional to the mass of dust particle, and if dust particles are under microgravity condition, then it must be ignored.

$$F\_{\mathfrak{g}} = m \mathbf{g}\_d = \frac{4}{3} \pi a^3 \rho\_d \mathbf{g} \tag{1}$$

where "g" describes the gravitational acceleration and "ρd" represents the mass density of dust particles. Mostly, its value for solid materials is ρ<sup>d</sup> = 2000 kg/m3 . This force can be neglected for submicron particles, but for the micron sized or larger particles, this can be considered as the dominant force that typically confines the time during which the particle resides in the plasmas.
