Dear Karishma,

welcome,

The refractive index of a composite material depends on the refractive index of both materials and their atomic mixing ratio. The refractive index is equal to the square root of the relative dielectric constant.

The dielectric constant of a composite material= x epsilonr1 + (1-x) epsilon2,

where x is the atomic ratio of material 1 in the composite. epsilonr1 and 2 are the relative dielectric constant of the two materials.

For more precise formulation for different states of the material please refer to the paper in the link:Article The Dielectric Constant of Composite Material—A Problem of C...

Best wishes