Very few of us ever stop to ask deeply scientific questions about our humble microwaves, but there is one curious thing that’s very relevant to how they work:
What’s the frequency of a microwave oven, and why does it operate at that frequency?
I don’t know about you but I’m always curious about this sort of thing, and so I set out to find the answers!
In this article I’ll explore some of the science behind our microwave ovens.
The frequency of a microwave oven
The simple answer to this question is that the frequency of a microwave oven is usually 2.45 gigahertz (GHz).
That’s equivalent to 2,450 megahertz (MHz) or 2,450,000,000 hertz (Hz) – just to answer the title of this article very specifically!
Why do microwaves operate at this frequency?
Manufacturers choose this frequency for one very simple reason: It’s the frequency at which water molecules resonate.
It’s this behavior that allows the water molecules to absorb the energy of the microwave radiation, and heat up your food in the process.
When microwave radiation is applied to food, the water molecules inside it vibrate very, very quickly. This in turn generates heat which spreads throughout the food.
For the curious who want to learn more, this process is called dielectric heating.
Although we’re mainly interested in agitating those water molecules, other polar molecules like fats and sugars can also absorb microwave radiation.
They do their bit to heat your food up too, but it’s mainly down to the frenzied activity of the water molecules.
That 2.45 Ghz frequency is chosen in particular because it provides the best possible balance between the amount of energy it generates, and how deeply it can penetrate into your food.
In fact, this energy level helps the microwaves reach several centimeters into the food.
If it couldn’t reach this depth you’d end up with very unevenly heated food. At the same time though, the energy is absorbed quickly enough that the outer layers of the food don’t get overcooked in the process.
Now you know that the frequency of a microwave oven is 2,450,000,000 hertz, and that it’s set this way for very good reason!
Without the dielectric heating process, a microwave simply couldn’t perform all the tasks we ask of it.