How Microwave Ovens Work Explained In Easy Terms

How microwave ovens work

Have you ever stared at the window of the magical box called a microwave oven while waiting on something to be warmed or cooked?

I catch myself doing that all the time.

And while I do that I often wonder how microwave ovens actually work?

Why does it have all those little holes in a mesh like window instead of just a plain window?

Aren’t the waves that’s supposed to be micro, escaping, straight into my eyes?

Well, wonder no more. In this article we will tell you all you need to know about the inner workings of a microwave oven.

Lets dig in!

In this article I will discuss:

A little bit of history

The first microwave oven, also commonly referred to as just microwave, was invented by Percy Spencer in 1946 from radar technology developed during the the Second World War.

While he was working on an active radar set he noticed that the candy bar inside his pocket started to melt.

The wave in microwave

A magnetron is the part in a radar, and microwave, that generates the microwaves.

How microwave ovens work
A magnetron, the wave generator

Without getting into too much detail, the magnetron uses electromagnetic fields to generate waves with a certain frequency and wavelength.

When Percy noticed his melting candy bar, he speculated that the magnetron could also be used to cook food.

A wave, after all, is the means to transfer energy through a medium without the transfer of matter.

Also, a wave oscillates, meaning it changes direction to and fro all the time.

The frequency of a wave is the number of times that a wave oscillates per second.

How microwaves heat up food

In almost all food you will find water.

Water is made up of positively charged hydrogen atoms and negatively charged oxygen atoms.

Due to this, water, and most other molecules, have a more positive charged side as well as a more negative charged side.

A wave basically has positive and negative sides as well.

How microwave ovens work
A typical electromagnetic wave

Positives charges attracts negative charges, so the positive side of the wave attracts the negative side of molecules and vice versa.

That causes the molecules to align in a certain direction.

But only for a moment.

That’s because the wave oscillates, which means its polarity changes.

With every oscillation, or switching of polarity, the molecules that were aligned, spin and realign.

So basically, as the wave oscillates, the molecules swing around.

That happens at the same rate, or frequency, as the oscillations.

This frequency is about 2.4 gigahertz (GHz) for microwave ovens. That is 2 400 000 000 oscillations per second.

The spinning and turning of the molecules causes friction between the molecules.

That friction, in turn, generates heat. And that is the heat that heats up the food.

Because the microwaves travel through food, it heats up from the inside.

Contrary to that, conventional ovens with elements heat up food from the outside and heat travels to within the food via heat conduction.

Why does a microwave have a turntable?

The easy answer to this is so food can heat up evenly throughout the whole dish.

Microwaves enter the microwave oven chamber from one spot.

From there, it bounces around inside the chamber off the inside walls. So you have microwaves flying all over the place inside the microwave oven.

That way food gets heated up more gradually compared to when you would have bombarded the food directly with microwaves from one angle.

Is a microwave oven safe?

So you have probably asked yourself if the microwaves can escape from the inside of the microwave oven.

The answer is that with an intact chamber, highly unlikely.

Many people have their reservations on the safety of microwave ovens when it comes to these waves. And rightfully so.

Microwaves, the actual waves, fall in the electromagnetic spectrum.

That is the same spectrum that includes the harmful gamma rays and X-rays. But visible light is also on that spectrum.

You can rest assure, though. Microwaves actually fall on almost the opposite end of the spectrum as gamma rays and visible light is in between.

It is very important, though, that if you notice any defects on the microwave, disconnect it from any power source and consult with a professional.


Microwave ovens are truly amazing devices.

It is right up there with the convenience factor.

As with any device it is important to observe common safety principles when using one.

If, for some or other reason, you have not used one or don’t own one, you are missing out.

It will make your life so much easier!