| A microwave oven works by passing microwave | | | | somewhat similar to heat from other methods. The |
| radiation, usually at a frequency of 2450 MHz , through | | | | rays from a microwave electrically manipulate water |
| the food. Water, fat, and sugar molecules in the food | | | | particles to cook food. It is actually the friction caused |
| absorb energy from the microwave beam in a | | | | by the movement that creates heat and warms the |
| process called dielectric heating. Many molecules (such | | | | food. The misconception arises because microwaves |
| as those of water) are electric dipoles, meaning that | | | | penetrate dry nonconductive substances at the |
| they have a positive charge at one end and a | | | | surfaces of many common foods, and thus often |
| negative charge at the other, and therefore rotate as | | | | deposit initial heat more deeply than other methods. |
| they try to align themselves with the alternating electric | | | | Depending on water content the depth of initial heat |
| field induced by the microwave beam. This molecular | | | | deposition may be several centimeters or more with |
| movement creates heat as the rotating molecules hit | | | | microwave ovens, in contrast to grilling ("broiling" in |
| other molecules and put them into motion. Microwave | | | | American English), which relies on infrared radiation, or |
| heating is most efficient on liquid water, and much less | | | | the thermal convection of a convection oven, which |
| so on fats and sugars (which have less molecular | | | | deposit heat shallowly at the food surface. Depth of |
| dipole moment), and frozen water (where the | | | | penetration of microwaves is dependent on food |
| molecules are not free to rotate). Microwave heating is | | | | composition and the frequency, with lower microwave |
| sometimes incorrectly explained as a rotational | | | | frequencies being more penetrating. |
| resonance of water molecules: such resonance only | | | | Most of people do not think about microwave spare |
| occurs at much higher frequencies, in the tens of | | | | parts when their domestic appliance breaks down. |
| gigahertz. | | | | They would usually get it fixed by a specialist who will |
| A common misconception is that microwave ovens | | | | buy the microwave spare parts and do the work for |
| cook food from the "inside out". In reality, microwaves | | | | you, or even will buy a new one. One option they tend |
| are absorbed in the outer layers of food in a manner | | | | to forget is they could fix it by themselves. |