Question

the process in which one kind of energy changes into another kind is called energy blank.

Explanation:

In the field of Physics (a subfield of Natural Science), the concept of energy transformation is well - defined. The process where one form of energy is converted into another form is known as energy transformation (or energy conversion). For example, in a light bulb, electrical energy is transformed into light energy and heat energy. So, based on this scientific concept, the word that fits in the blank is "transformation" (or "conversion").

Answer:

transformation (or conversion)