Last week we explored the three main ways that thermal energy can DIFFUSE through our food during cooking:
Radiation is the transfer of waves of energy from every ATOM in the universe.
Conduction is the transfer of thermal energy between two or more objects that are touching each other.
Convection transfers energy through fluids (this means a gas or a liquid.)
Now it is time to see who wins between the push-button speed of microwave ovens and the all-time favorite – the conventional oven!
Naturally, we will be using the four main concepts of science within our study of these two culinary devices:
It is important to note that all of these methods of heat DIFFUSION follow the LAW OF CONSERVATION. We never create or destroy any thermal energy when we are cooking. However, a lot of thermal energy can be lost into the environment. You can notice this whenever you get near a hot oven… the air around the oven is warm because thermal energy is escaping into the environment!
You learned last week how the tradition oven works to bake our food:
Baking uses two of these forms of heat transfer: Radiation and Convection. Thermal energy is released from the electrical coils or gas flames of an oven in the form of radiation which heats up the food. In addition, some of this radiation DIFFUSES into the metal walls which heats up the air inside the oven itself. This is how convection heats the food within the oven. As the air (a fluid) is heated, it DIFFUSES some of its heat into the food as well.
Microwave ovens do something entirely different in order to cook our food. In fact, this kitchen appliance only uses radiation to heat our food.
To be perfectly honest with you, I could probably spend pages working on how a microwave oven works. So let me give you the shortened version:
A microwave sends out billions of waves of energy (radiation) towards your food every second. The water molecules within your food are vibrated back and forth by these waves very quickly. With all of these ATOMS in constant motion, they bounce into all of the other molecules in the food. This motion creates a lot of friction, which in turn, increases the amount of thermal energy within the food. It doesn’t take long for this large amount of thermal energy to DIFFUSE throughout the food!
Friction is a force that is created between two objects that are rubbed together. The greater the friction between two objects, the greater the thermal energy that is created! Friction is the reason your hands warm up when you rub them together.
To sum this up: Foods that contain water are heated very quickly by a microwave!
SO WHY IS THE CONTAINER INSIDE MY MICROWAVE ALWAYS SO HOT? IT IS NOT MADE OF WATER!
A microwave may easily heat up your food; however, it does not heat up the container at all (or the air.) The bowls you place in a microwave are heated as thermal energy with the ATOMS is DIFFUSED into the container because of the process of conduction.
SO WHICH METHOD IS BETTER?
Both methods have their good and bad points. Microwaves can cook food much faster because they are not slowed down by the DENSITY of the food being cooked. By this I mean that microwave radiation can reach deeper into the food than the radiation produced by a traditional oven.
However, since a microwave can heat up our food much faster, it also can dry out our food much faster too! It also cannot turn our Thanksgiving Day turkey a golden brown color because a microwave cannot make the surface of our food any warmer than its interior. This is very important if you want to brown your baked foods!
So who wins this battle? I say they BOTH win. A traditional oven is best suited for slow cooking and baking our foods to a juicy, tender result. And the microwave is best for reheating or preheating foods that don’t require long amounts of cooking.
Personally, I wouldn’t want to live without BOTH of them!
Learn more about physical science concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!
