Hello guys! Today we would be talking about how the microwave oven works and I hope to allay most of your fears and the myths attached to the use of microwave ovens in our various homes.
Microwave oven is known in our various homes as microwave simpliciter. It has proven itself to be a very vital tool in our kitchens especially when we want our favourite snack or popcorn for that “Netflix and chill” moment and I believe most of us may not be able to do away with the microwave oven.
The microwave oven is an electric oven that heats and cooks food by bombarding it with electromagnetic radiations which fall within the range of the microwave frequency range which accounts for the name microwave oven.
The electromagnetic waves generated causes the polar molecules (molecules with negative and positive ends like water, fat etc.) especially the water molecules within the food to vibrate and rotate vigorously thus generating heat. This is known as dieletic heating. This is basically how it works and the reason why a dry empty ceramic or microwaveable dish placed in a microwave oven after sometime remain cold because it contains no water in it or at the molecular level.
The microwave oven is made up of a high voltage power source; a high voltage capacitor connected to the magnetron; a cavity magnetron which converts high voltage electric energy to microwave radiation; a magnetron control circuit (usually with a microcontroller); a short waveguide (to couple microwave power from the magnetron into the cooking chamber); a metal cooking chamber; a turntable or metal wave guide stirring fan; and a control panel.
Thus it is evident that it does not contain any radioactive source as purported by some individuals who get the chance to come on air to pass such comments.
The electromagnetic waves (mind you, which are radio waves) generated in the oven are similar to what your mobile phones, Bluetooth and wireless devices (e.g. PS4 controller, sound bars, air pods, cordless mouse and keyboards etc.) produce. Frequencies, however, are in one of the ISM (industrial, scientific, medical) bands, which are reserved for this use, so they do not interfere with other vital radio services.
In talking about the hazards and benefits of using a microwave oven, the latter outweighs the former. Despite the risk attached to exposure to the microwaves, the cooking chamber is similar to a Faraday cage to prevent the waves from coming out of the oven. Even though there is no continuous metal to metal contact around the rim of the door, choke connections on the door edges act like metal to metal contact, at the frequency of the microwaves, to prevent leakage. The oven door usually has a window for easy viewing, with a layer of conductive mesh some distance from the outer panel to maintain the shielding. Because the size of the perforations in the mesh is much less than the microwaves’ wavelength (12.2 cm for the usual 2.45 GHz), microwave radiation cannot pass through the door, while visible light (with its much shorter wavelength) can.
Also, direct microwave exposure is not generally possible, as microwaves emitted by the source in a microwave oven are confined in the oven by the material out of which the oven is constructed. Furthermore, ovens are equipped with redundant safety interlocks, which remove power from the magnetron if the door is opened.
This safety mechanism is required by United States federal regulations.
According to the United States Food and Drug Administration’s Center for Devices and Radiological Health, a U.S. Federal Standard limits the amount of microwaves that can leak from an oven throughout its lifetime to 5 milliwatts of microwave radiation per square centimeter at approximately 5 cm (2 in) from the surface of the oven which is far below the exposure level currently considered to be harmful to human health.
Article written by Sidney kojo, a food scientist with a BSc in Food nutrition & science from University of Ghana.
1. “Microwave Oven”. Encyclopedia Brittanica. 26 October 2018. Retrieved March 27, 2019.
2.https://en.wikipedia.org/wiki/Microwave_oven#Principles. Retrieved March 27, 2019.