Like most of you I’m not sure how I’d cope without my microwave, but I’d never really thought much about how it actually works!
How do microwaves transfer energy to your food, and what is it about them that makes them such a convenient way of prepping quick meals and reheating leftovers?
It all starts with a component of your microwave called a magnetron.
This is usually located at the top of your microwave, and first of all channels energy from your power outlet into a heated element.
This in turn creates a flow of electrons that generate invisible microwaves. These waves are then transmitted into the microwave interior using an antenna.
This video does a really good job of explaining the basics of how microwaves work, and will answer all your questions:
With me so far? Good!
Now we’ve got a source of energy though, how do these microwaves transfer energy into our food and heat it up so conveniently?
Once the waves are inside the microwave itself, they bounce all around the insides, and then heat the food using what’s known as radiation heating.
All this energy bouncing around penetrates into the food and liquids, and “excites” the molecules they’re made of.
This energizing effect generates heat, which then spreads throughout the food. Or at least, that’s the plan.
The energy can only penetrate so far into the food, which is why you so often end up with a piping hot exterior and a much cooler interior.
Most often, of course, you can solve this by simply microwaving in short bursts, and regularly stirring the food. That helps everything get exposed directly to the energy source.
Otherwise you’ll find your microwave heats your food unevenly. On the flip side of the coin, microwave for too long and you’ll develop very, very hot spots with unpleasantly cool areas too.
Frequently Asked Questions
That’s the very simple answer explaining how microwaves transfer energy! Before wrapping things up, I’ll answer some related questions that often come up alongside this topic.
What is microwave energy?
Microwaves are a kind of electromagnetic radiation.
This energy is particularly useful for cooking, as it’s absorbed by food, reflected by metal, and passes through typical – microwave-safe – cookware.
Is microwave energy heat?
When it’s generated, microwave energy has the form of electromagnetic energy.
It’s the agitation this energy causes to your food’s water molecules that creates the heat which then spreads throughout the rest of the food.
Are microwaves energy efficient?
The answer to this depends – logically enough – on the precise appliance you own.
I found a really interesting article on CNET which looks at this in more detail.
The author found that their microwave used 1,200 watts per hour of use, compared to the 3,000 watts drawn by an electric oven.
So, comparing these two very common cooking methods, it’s easy to conclude that microwaves are indeed energy efficient.
The devil will always be in the detail! From a general perspective though, I think it’s fair to describe microwaves as energy efficient.
How much energy do microwaves use?
This is one of those “how long is a piece of string” questions I’m afraid.
The amount of energy your microwave uses will very much depend on the make and model you own, and how you use it.
Helpfully, I found a good calculator online that lets you add your microwave’s power rating, your energy prices, and the hours of daily use.
Plug those in and you’ll get the answer you need for your own unique circumstances.
Is microwave energy dangerous?
The FDA has a great resource that explains what you need to know about microwaves and health.
The short version is that if you were directly exposed to high levels of microwave energy, it could burn body tissue. In normal use though, this really isn’t going to be a problem.
Do watch out for hot spots in your food though! You’re far more likely to temporarily burn the roof of your mouth than do any lasting damage to your health.
Can microwave radiation go through walls?
Yes, but there’s nothing to worry about when it comes to your microwave oven.
The radiation can’t pass through the metal sides of the appliance, and you’ll notice a mesh in the clear door which acts as a shield.
This is assuming, of course, that your microwave isn’t damaged. Always think twice before using any kitchen appliance that is showing any signs of serious wear and tear!
Now you know how exactly microwaves transfer energy, along with a little extra knowledge on what’s really going on inside your appliance.
Mark’s a lifelong food fanatic and spent ten years working as an entertainment journalist. He now combines his love of food, drink and writing as the founder and editor of Viva Flavor. Read more