The interface is usually a few molecules thick but its area depends on the size of the particles of the bulk phases.
*What is Area of interface? What is its sense and How is it defined.I mean if we have two bulk faces with significant difference in particle size,and we define surface area for one layer then it is surely not the same as that for the other layer then how that area of interface make sense.
One of the explanation (or i should rather say an example) i found on internet is oil dressing on salads ,where interface is spherical having less surface area.
Now that example is itself confusion because it is mathematically proved that for any given volume sphere has least surface area, then how is that area being less attributed to particle size?