February 4

Why Does an Empty Plate Not Heat up in the Microwave? | The Science Behind This Explained in Simple Words


Author: Gisele Perez
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The question "why does an empty plate not heat up in the microwave?" is a very common question and one that people probably do not think they will ever have to know the answer to.

However, it is an important thing to understand because microwaves are a form of electromagnetic radiation used in many different appliances today.

Microwaves are electromagnetic waves with high frequencies. They produce energy by vibrating the water molecules that are found in food. When not much is present, there aren't many water molecules to vibrate; therefore, little energy is released.

Microwaves do not heat objects as they are non-polar materials. Only polar materials can be heated up by microwaves, meaning they have a positive and negative sides.

Why Does an Empty Plate Not Heat up in the Microwave: Can You Heat Empty Plates in a Microwave?

Yes, you can heat an empty plate in a microwave, but it is not the most efficient way. Heat would be released when more molecules vibrate or collide with each other. Also, when microwaves pass through an area that already has hot food, they release energy into that area, and it becomes more desirable than when you turn on the microwave.

However, it might not be safe to heat an empty plate in a microwave since microwaves can be dangerous. When you turn on a microwave, it emits microwaves that bounce off the walls and all other metal objects inside it (which includes your empty plate).

The energy produced by these microwaves can go through walls and other things between you and the microwaves. You are exposed to these waves when they hit your plate. For this reason, there are safety precautions to keep the microwaves inside until the device is turned on with food inside.

The safest way to heat an empty plate would be by putting it in the oven or on top of a stove. Both of these cooking appliances emit heat instead of microwaves. A microwave is an oven, but a regular range puts off heat instead of microwaves. You can put almost anything in an oven or on top of a stove. It will get hot because the heat given off from these appliances heats objects instead of microwaves heating them.

What Are the Reasons Why an Empty Plate Does Not Heat up in the Microwave?

There are a few reasons why the plate doesn't heat up in the microwave when there is nothing on it. The first reason is that microwaves cannot penetrate non-polar surfaces. That means that they cannot produce any energy when contacting these surfaces, such as an empty plate.

Another reason is that microwaves only penetrate deep into the material when liquids are present. For example, when you put water into a glass and heat it in the microwave, the heat can spread deep down because of its liquid state.

When an object is placed inside a microwave, microwaves are reflected off the surface of the things, which leads to them bouncing around the kitchen appliance. That's why when you heat food in the microwave, it's common to hear popping noises.

Use a Plate with Silver Inlay

Pour some water into the plate you would like to heat up and then place it in the microwave. You will notice that it heats up because water is polar, meaning microwaves can produce energy by vibrating the particles back and forth.

Therefore, it heats the food inside your plate and heats the vessel itself. Silver is another polar material, which makes it possible to heat the silver inlay on your plates. Additionally, this factor allows you to heat an empty dish. It also explains why metal spoons or forks heat up in the microwave.

Why Do Paper Plates Not Heat up in the Microwave?

A paper plate is not heated up in microwaves because it is a non-polar material. Paper has no positive or negative sides, which means microwaves cannot heat it.

Red Disposable Plates Get Hot in the Microwave

Although red disposable plates look like paper plates, they heat up in microwave ovens. Its because there are ions inside the plate that gives it some polarity. However, this isn't enough to produce energy that heats the plate and food. Microwaves have some ionization in plastics but are negligible.

Is the Plate Not Heating up Because It Is Made of Ceramic?

Some plates are made of ceramic. This material has some conductive properties but is not enough to make the material heat up in microwaves. It is because ceramic plates are made from a mix of non-polar objects, causing them to heat up in microwaves.

Cooking in Microwave Ovens

Cooking in microwaves can have some benefits that traditional ovens cannot provide. For example, cooking in a microwave oven takes less time because the energy is focused on one side of your food items. This way, it speeds up the process of heating your food without overcooking it.

On the other hand, microwaves are less reliable at cooking a whole meal. For example, the oven might heat one side of your roast vegetables exceptionally well but not the other side because it's weak. That is why food needs to be turned around halfway through cooking or taken out and put back in multiple times during the process.

Although microwaves are suitable for heating portions of your meal like drinks or sauces, they are not ideal for cooking meat. For example, you can cook a steak one side at a time by placing it in the microwave oven. However, the result will be very dry because microwaves cook food on the outside first and don't penetrate deep down to heat the inside of your steak.

The Science Behind Vibrating Molecules

When you heat food in the microwave oven, what is happening is that your food's molecules are rapidly vibrating within their container. The rapid vibrations cause increased pressure inside the microwavable object due to the air particles bumping into one another. It creates hot spots on your plates or bowls where you see steam forming.

However, microwaves cannot heat an empty plate because there are no molecules present on the surface that are capable of vibrating. For this reason, you should always put food onto your dish before heating it in a microwave oven.

If you place an empty plate into the microwave, it will get hot because the hot air particles collide on the dish's surface and heat your plate this way. It is not a very efficient way of heating food in a microwave oven because some energy is lost along the way to the inside of your meal due to molecules present vibrating.

In addition, as far as microwaves go, we also reviewed different types of modern microwaves, so you can check out what model best suits your needs. Check out the extracts from those reviews we shared here:

Microwave Types

Best Convection Microwave

Convection ovens have great cooking power, a child safety lock to prevent accidental usage of the microwave, and different cooking levels. Like we mentioned before, choosing a convection microwave for your needs will be influenced by these 3 main factors - capacity, features for your budget, and your counter space.

Best Microwaves For Home Use

The more features you choose to have, the more expensive the microwave oven for home use would be. The good news is that you can choose to keep things very economical by simply going for a microwave oven with minimal features that meets the size and power requirements as stated earlier.

Best Simple And Basic Microwave Ovens

To reiterate this, a basic microwave oven, in our opinion is a small to midsize, non-inverter solo countertop microwave oven. Why? because a microwave such as this is easy to operate, is affordable, does not occupy much counterspace and is easy to install.

Best 1200 Watt Microwave Ovens

Most of the ovens in this category are quite expensive. This is generally due to two reasons: high powered microwave ovens are heavy duty and thus feature expensive components, secondly, they are very large. Some of the premium ovens in this power category though offer cutting edge technology, albeit at a higher cost.

Best Midsize Countertop Microwave

A midsize model is excellent for a regular family. The smaller models are generally reserved for offices, dorm rooms or garage like spaces. Larger microwave ovens are reserved for commercial spaces, so if you are have regular sized family or 4-5 members, then a midsize microwave oven would work perfectly for you.


Because the paper is made from non-polar molecules, microwaves do not heat paper plates. Ions inside red disposable plates make them heat up in microwaves. Ceramic material has some conductive properties, but microwaves cannot heat it.

Microwave ovens can have some benefits that traditional ovens cannot provide, such as cooking food on one side for a short period. On the other hand, microwaves are not very good for cooking meat. Lastly, an empty plate will get hot because air heats it.

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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