Question:How do ovens actually cook food?
Food cooks when its temperature is raised and chemical reactions happen.
The chemical reactions change the food from it's raw or uncooked food into it's cooked form, which is usually quite different in appearance.
So to Cook food we must supply the energy to the food, which is needed to increase it's temperature.
How the food is warmed depends upon what type of oven you are using.
All ovens cook using electromagnetic radiation to transfer energy to the food in order to raises the food's temperature.