How Does A Microwave Oven Work?

From energy to heat

Microwave ovens use electromagnetic energy in the form of microwaves, similar to radio waves, to produce heat. Microwaves cause food particles to vibrate quickly, creating friction that produces heat, which in turn cooks the food.

Microwaves are colorless, odorless, and tasteless, and are not radioactive (a common myth when microwave ovens first came on the market).

Here are three basic facts about microwaves:

Microwaves have the ability to pass through plastic, glass, and paper.

Microwaves reflect metal surfaces (which is why you can't place anything metal in a microwave oven).  The metal walls within the oven form a cavity resonator.  This creates a balance, or equilibrium, within the cooking space. 

Microwaves have the ability to penetrate food products.

Now, let's take a look at how microwaves are converted from electricity and how they are able to operate within a confined oven.

Turn it on

Microwave ovens can be broken into two main parts: the control section and the voltage section.

The control section is comprised of the timer and the system that governs the power output.  Electricity passes from the outlet, through the power cord, and into the microwave.  The electrical path extends to a series of interlock switches.  If the oven timer is turned on, the electricity extends to the control circuits. 

The voltage section deals with the energy flowing through the oven, which passes through the magnetron tube, in turn affecting the amount of voltage, or power, released as microwaves in the oven. The high voltage transformer is able to transform a standard 115 volts to a whopping 3000 volts, which is needed in the magnetron tube to convert electricity to electromagnetic cooking energy. 

Releasing the energy

Once the energy has been produced, it still needs to be released into the oven.  This happens as it passes from the magnetron tube into a channel called a waveguide.  The waveguide then releases the microwaves into the food compartment, which are dispersed evenly by an antenna, or a revolving carousel. 

Don't be alarmed

In the 1970s, it was commonly thought that microwaves could cause cancer and other illnesses.  Not true!  The microwaves present in the oven immediately stop being emitted as soon as the door opens.  The microwaves never leave the oven, so they can't harm you in any way.

More information on microwaves