What Is a Microwave Oven?

Cooking Concepts

• A microwave oven utilizes a magnetron inside the unit to convert ordinary electricity into short radio waves as a 2450 megahertz frequency. Vibrations are caused in the food by the electromagnetic waves to heat the food. Some food molecules heat faster than others; fats and sugars heat the fastest in a microwave oven. Microwaves are distributed throughout the oven by fans.

Heating

• Foods are heated with microwave energy through friction as opposed to convection, conduction or radiative heat transfer. Moisture molecules in the food orient themselves to the microwave field by rotating. Working with negatively charged oxygen atoms and positively charged hydrogen atom, the water molecules continue to re-orient themselves to the negative and positive ends of the microwave field. The field polarity changes at a rate of 2450 megahertz, which is approximately 2.45 billion times per second. This causes the friction which in turn heats the food.

Power Levels

• Microwave ovens offer different cooking power levels. For cooking foods completely, 100 percent power is usually chosen. Thawing frozen foods when cooking completely is not the intent is generally done as 30 percent power. The magnetron in a microwave oven produces the highest amount of energy at 100 percent power. To achieve the lower power levels, the magnetron cycles off for a percentage of time. For example, when set at 30 percent power, the magnetron operates at full power for 30 percent of the time and cycles off for 70 percent of the time.

Resting Time

• Due to the way that microwave ovens heat and cook, food needs to "rest" for a period of time after removing it from the oven. The vibrations of the water molecules that cause the friction which heats the food are still active for a period of time until they settle. The food is actually still heating through during this period of time. Most microwaving directions will indicate the length of this period of time.