Nanoparticle size range [ 20 nm and 250 nm both with spherical morphology ] , .There are many equations available for Rayleigh to calculate scattering intensity [ where the size parameter x 1 [ i.e 2*pi*r / lambda is > 1 ] , in that case i should depend on Mie approximation , i have used rayleigh eqn as given in this website , i need to use Mie approx to calculate scattering intensity [a.u] for particle size of 250 nm , can anybody suggest some equation to calculate scattering intensity using Mie theory .