Field Vectors and the Maxwell Equations

As stated in the introductory chapter, we adopt a macroscopic approach to the problem of determining absorption and scattering of electromagnetic waves by particles. Therefore, the logical point of departure is the Maxwell equations for the macroscopic electromagnetic field at interior points in matter, which in SI units may be written  

Equations (2.1)-(2.6) are not sufficient in themselves they must be supplemented with constitutive relations, which are assumed to have the form 

We shall not, however, assume that the phenomenological coefficients are independent of frequency. To provide some insight into this assertion, we must digress briefly. Consider, for example, the susceptibility. The polarization P is 

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