February 22

What is a Microwave Oven? – Quick Guide


Author: Gisele Perez
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Just a few centuries ago, before the invention of the microwave oven, people had to rely on other methods of heating that would seem crude and inefficient to most people today.

For starters, you would have had to start a fire, endure the smoke, and even more painfully, watch as your food gets burned because you forgot to take it out on time.

Thanks to Percy LeBaron Spencer, the inventor of a microwave (see ‘When Was Microwave Invented?’ article), the only thing you may need to worry about now when it comes to warming your food, is how hot you want your food to be.

Let us further learn about what is a Microwave Oven.

Also Read:

History of the Microwave

It may come as a surprise but the technology behind the modern microwave oven was born from the necessity of short-range radar technology during World War II.

During this period, magnetron tubes were built to generate these waves and as the war drew to a close, the surplus tubes, as well as the technology, were of little to no use.

Percy LeBaron Spencer accidentally discovered the potential of using these microwaves for culinary applications while working as an engineer at a company called Raytheon.

The idea was already there before his discovery, but while visiting one of the labs that was testing magnetron tubes, a Peanut bar in Spencer’s pockets began to cook.

This accident got him curious and after some tests, he was able to replicate the effect with a bag of popcorn and an egg among other things.

With Spencer’s contribution in numerous experiments, improvements were made and in 1946, Raytheon introduced the first commercial microwaves.

What is A Microwave Oven
Raytheon Radarange III of 1955 – one of the earliest microwave ovens. Source: Getty Images

These first devices were bulky, noisy (see ‘How to Mute Microwave‘), expensive and built for commercial use in restaurants.

A couple of decades later, microwaves were significantly cheaper and started becoming a common household and commercial appliance. Today, microwave ovens come in more compact sizes, are more affordable, and are equally more efficient (see our ‘Hamilton Beach 1000 Watt Microwave Review‘). 

If you are someone who is looking for the optimal kitchen setup and need to make best of the space you have there, a mounted microwave oven is a great way to utilize space, as explained in our ‘How to Mount a Countertop Microwave Under Cabinet‘ post. It will also help when it comes to ventilation systems, which we talked about in ‘Convertible vs Recirculating Microwave Vent‘ review.

What is a Microwave Oven?

A microwave oven is an electronic appliance that makes use of relatively low-frequency waves to cook food.

The basic principle is that these electromagnetic waves are absorbed by certain molecules in our foods, like water and some fats. On another note, some food could trap electromagnetic energy which will eventually break down in a flash, causing flashes or sparks, as explained in our ‘Why Do Grapes Spark in the Microwave?‘ post.

These molecules get energized and begin to vibrate. As a consequence, heat is produced and the food gets hot. Also, as explained in our ‘Galanz Microwave Air Fryer Review‘, today’s technology enables you to bake, roast, and microwave food in one combined unit.

Microwave Oven Vibrates
Microwave oven vibrates molecules inside the food. Image Source: Scientific American

Some of the places where this effect comes in handy include:

Heating Food

As soon as your food leaves the flame, it starts getting cold. Some foods are easily eaten cold. However, for certain foods, warming is essential.

In such a case, you would need a faster solution that can get the food piping hot in just a matter of seconds, or just a few minutes at most (see ‘Is A 900-watt Microwave Powerful Enough?‘).

Unlike other methods that heat food from the outside in, microwaves penetrate the food. The food gets heated faster, both inside and out. Also, convection ovens have added an extra heating element and fan to the microwave technology, making them more efficient and faster at preparing and reheating food (see ‘Are Convection Microwaves Worth It?‘).


Freezing is one of the few methods that can be used to preserve fresh food for long periods without the need for additional preservatives.

A microwave oven can come in handy when you need to quickly thaw certain types of food.

As opposed to waiting for the food to thaw out naturally, a few minutes in a microwave oven can have the same effect and save you a lot of waiting time.


Depending on the model you have, you can also use your microwave oven for cooking. Versatile ones can be used to grill, bake and roast food and can last a good long time if taken care of well – check out ‘How Long Do Microwaves Last?‘ and ‘How Long Should a Microwave Last?‘ posts.

As a result, you may end up not needing your stove (see ‘How to Install a Microwave Oven Over the Stove?‘ post) for some meals that can easily be handled in a microwave.

Sterilizing Sponge

Those electromagnetic waves can do more than just heating your food. Microwave ovens can also be used to sterilize some household equipment like sponges.

This should be done with a lot of caution to prevent any accidental fires, burns or damage to your microwave.

The first step is ensuring that the sponge is completely wet and that it contains no metallic components.

Warming Beauty Products

Some cosmetics tend to harden, especially when exposed to cold temperatures like during winter. A useful hack is to use a microwave oven to liquefy the solidified products.

You should not leave the product inside (see ‘What Paint Is Used Inside a Microwave Oven?‘ post) for too long though as you may end up with a mess. Just a few seconds should do.

Myths About the Microwave Oven

Despite the many concerns people raise regarding the use of microwave ovens for cooking, it has remained to be proven that these devices pose any health risk when used as intended (see also ‘Do Microwaves Cook From the Inside Out?‘).

Granted, mishandling can cause harm to the user.

Nevertheless, they are proven to be quite safe (see ‘Are Old Microwaves Safe? ‘ post, too). Here are some popular myths about the microwave oven.

They Can Cause Cancer

The truth is, microwaves are all around you, not just inside the microwave oven. They are the typical waves used for mobile communication.

These waves belong to a category of radiation known as non-ionizing radiation. This means that they lack the energy to alter the molecular makeup of your cells, unlike other forms like gamma rays.

Since the waves are more concentrated inside the unit, in the case that a leak occurs, the worst you can get away with are some burns. Not cancer. Both FDA and WHO have designated microwave ovens to be safe IF used according to manufacturer guidelines.

Also Read: How much radiation does a microwave oven emit?

Microwaving Food Destroys its Nutrients

It is a fact that cooking food in any way causes a reduction in some of the available nutrients.

However, it is misleading to imply that this effect is enhanced when using a microwave oven.

The leaching of nutrients out of food depends on the temperature at which you cook the food as well as how long the cooking lasts.

Also, some cooking methods especially those that use water (boiling, stew etc) can be more wasteful. Cooking in a microwave means less use of water as well as less time used. So you may end up retaining more nutrients as opposed to boiling. Nonetheless, to get a full picture of this dilemma, we recommend reading our earlier ‘Does Microwaving Food Kill Nutrients?‘ post.

Microwaving Makes Food Radioactive

ionizing vs non ionizing radiation
Microwaves are safe non-ionizing radiation. Source: Mirion.com

This one is so popular that at one point in time, cooking food in a microwave was referred to as “nuking”.

To debunk this, we need to understand how the microwave works.

The simple explanation is that the waves make some molecules in the food vibrate and heat energy is produced that in turn cooks the food.

No molecular structures are changed and thus no genetic structure or chemical bonds are broken. This is because, as mentioned earlier, microwaves are non-ionizing radiation.

Precautions When Using a Microwave

Like most electronic devices, microwave ovens have downsides that come with numerous functions (check out ‘What Is Sensor Cooking?‘ post) and modes that have frustrating beeping noises (see ‘What Does SE Mean on a Samsung Microwave Oven?‘).

There are also a few things you need to consider when using a microwave. First, avoid putting anything metallic inside the device as this can cause sparks and in extreme cases, explosions (see ‘Why Does Metal Spark in a Microwave?‘)!

It’s equally advisable to avoid heating food in plastic containers unless they are microwave-safe (see also ‘Can you Microwave Ceramic?‘).

Ensure you cover your food when heating it to avoid the occasional splattering and beware, thawing solid foods in a microwave can cause partial cooking.

Lastly, DO NOT use a faulty microwave oven. Read our guidelines such as ‘Microwave Turntable Turns When Door Is Open‘, to learn how to fix the issue if it can be fixed, to begin with. Most importantly, DO NOT give a faulty microwave up for sale or donation either. 


Microwave ovens are versatile devices with plenty of uses at home (see also ‘Where to Put Microwave in Small Kitchen?‘). Without them, some cooking tasks would have been much harder and would have as well taken a lot of time though you should still check out our ‘How to Cook Microwave Food Without a Microwave‘ post.

In this article, we had a bird-eye view of what is a microwave oven. We did not go into the specifics of how it works, instead we just reviewed the appliance itself.

While its invention was more of an accident, its value continues to strike us as one of the most useful kitchen equipment (see also ‘Air Fryer vs Microwave‘).

Using one is very straightforward, and with a few precautions taken, you can be sure that the device will continue to serve you for a long time.

About the author

Gisele Perez

When not giving in-home, hands-on cooking classes, or developing recipes, Gisele "cooks" wonderful posts for us. She writes about various topics related to cooking appliances and cooking methods.


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