For orientation, please consult the attached two relevant Wikipedia articles. For the theoretical modelling of the problem, I refer you to the attached publication (the 3rd link below) by Van den Berg, De Hoop, Segal and Praagman, which concerns hyperthermic cancer therapy.

http://en.wikipedia.org/wiki/Dielectric_heating

http://en.wikipedia.org/wiki/Microwave_oven

http://atdehoop.com/Papers/DeHoopAT_paper_1983_02.pdf

The absorption of radiation by food cooked at a kitchen microwave oven is mainly due to the dielectric loss associated with dipole relaxation by water molecules. Interestingly enough, the microwave frequency range used avoids the maximum of the absorption curve since otherwise the outer layer of the food would be quickly overcooked compared with the core. The corresponding theory can be found clearly explained by Michael Vollmer, at the paper entitled "Physics of the microwave oven", published at "Physics Education" in January of 2004 (Vol. 39, Nº 1, pp. 74-81): http://iopscience.iop.org/0031-9120/39/1/006

Thank you responded Academicians