Microwave ovens produce heat directly within the food, but despite the common misconception that microwaved food cooks from the inside out, 2.45 GHz microwaves can only penetrate approximately 1 centimeter (0.39 in) into most foods. The inside portions of thicker foods are mainly heated by heat conducted from the outer 1 centimeter (0.39 in).
In most ovens, the magnetron is driven by a linear transformer which can only feasibly be switched completely on or off. (One variant of the GE Spacemaker had two taps on the transformer primary, for high and low power modes.) Usually choice of power level doesn't affect intensity of the microwave radiation; instead, the magnetron is cycled on and off every few seconds, thus altering the large scale duty cycle. Newer models use inverter power supplies that use pulse-width modulation to provide effectively continuous heating at reduced power settings, so that foods are heated more evenly at a given power level and can be heated more quickly without being damaged by uneven heating.
The Breville’s accuracy and customizability were unmatched in testing. Because microwave heat conducts from the outside in, you’ll usually get rubbery edges if you don’t lower power to allow the heat to seep in further. But with the Breville, if something starts boiling over, you can use its power level and time dials in the midst of cooking and let the heat penetrate.
A microwave oven (commonly referred to as a microwave) is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces polar molecules in the food to rotate and produce thermal energy in a process known as dielectric heating. Microwave ovens heat foods quickly and efficiently because excitation is fairly uniform in the outer 25–38 mm (1–1.5 inches) of a homogeneous, high water content food item.