Internal Voltage Levels in Microwave Ovens

Primary Components of a Microwave Oven

• The primary components of a microwave oven are the case, including the cooking chamber, the magnetron, a high-voltage transformer and a console or operating device. The magnetron tube actually converts electricity to microwaves. The transformer and related circuitry take 120-volt household current and boost the voltage to the 3,000 to 5,000 volts necessary to produce microwaves. The operating device may be a simple switch and timer mechanism. Many microwave ovens allow the user to vary the cooking voltage for tasks such as thawing meat.

Transformer: The Workhorse of the Microwave Oven

• The transformer is an electrical device that modifies alternating current by increasing or decreasing electrical potential or voltage. When you plug your microwave oven into a standard household outlet, the oven is supplied with 120 volts, alternating current (120VAC). The current is passed through a copper-wire coil in the transformer. The moving electrons generate an electromagnetic field surrounding the primary coil. A secondary coil, with a different number of wraps, is positioned in the electromagnetic field. Electromagnetic induction causes current to flow in the secondary coil. The voltage of the secondary current is proportional to the relative number of copper-wire windings in the primary and secondary coils.

Voltage Necessary to Produce Microwave Radiation

• Magnetrons in current household microwave ovens operate at a nominal frequency of 2450 MHz. To produce radiation at this frequency, the transformer must supply the magnetron with current of about 3,000 to 5,000 volts. Professional-grade microwave ovens may be supplied with a 220-volt current and produce microwave radiation with higher frequency, allowing food to cook significantly faster than in a household microwave oven.

Basic Heat Production with Microwaves

• Microwaves, produced in the magnetron, are partially characterized by their ability to interact with matter, including food, at the molecular level. In short, when the microwave radiation interacts with food, the food molecules become physically agitated. Friction of the moving molecules generates heat, which cooks the food.