Here's why:

* Infrared radiation is a type of electromagnetic radiation that falls within the range of wavelengths that can heat objects.

* The heating elements in a conventional oven, whether they are electric coils or gas flames, generate infrared radiation. This radiation is then absorbed by the food, causing its molecules to vibrate faster and thus increasing its temperature.

While there might be some other forms of electromagnetic radiation present in a conventional oven (like light from the oven bulb), these are negligible in terms of their contribution to heating the food.