Why do microwave ovens cook so rapidly?
When you put solid food (a potato, not soup) into a conventional oven, the heat flows slowly into the center of that food. This heat must work its way into the food via thermal conduction, in which adjacent atoms and molecules transfer their motional energies in a long bucket-brigade process. The last part of a potato to become hot is its center. However, in a microwave oven, the microwaves travel well into the solid food and deposit their energy everywhere. The potato cooks throughout at a relatively even rate. The actual amount of heat and energy involved in conventional and microwave cooking is about the same. However, the microwaves can heat the food throughout without having to wait for the slow process of conduction to carry it inward from the food’s surface.