Geometrical characterization of a particle

Although rigid, the size of a solid particle is not easy to define if the particle is not spherical. However, its volume or area can be quantified, provided it is possible to measure the same. The size of the spherical particle is defined by its diameter D, based on which its volume Fp and areaAp are e q)ressed by  

We also define the specific area of the particle as the ratio of its area to its volume  

For a sphere, Op = 6 D. It is important to note that the specific area does not have the dimension of a length, but is instead represented as the reciprocal value of a particle s length. The smaller the particle, the greater will be its specific area. The relevance of this concept is apparent as we understand later on in this discussion. 

Although we cannot simply define the size of a grain of aibitraiy geometry, it is easier to define the size of a non-spherical particle by referring to its volume, its 

In short, the equivalent sphere is often used to define the size of a particle. 

---