How does an object scatter or absorb electromagnetic radiation? A very elegant analytic solution can be found for a single sphere with the Mie coefficients. In this thesis, an approach is used that is very similar. The amplitudes of the incident and scattered fields are connected by the T-matrix. We present a method to obtain the T-matrix of arbitrary objects. Furthermore, an extension is shown, where the scattering from several of such objects forming a cluster can be calculated.