The theories that combine two different approaches in dealing with interacting objects, for instance, treating electromagnetic laser field classically, and the interacting atom as a quantum object, have some ambiguities and, as such, they should be labeled as “mixed”. From the Noether's Theorem Corollary, which we proved earlier, about the conservation laws of energy, momentum and angular momentum in mixed theories, follows that the aforementioned theories do not support the law of angular momentum/spin conservation (to be precise, the obtained result does not imply that the law of conservation of angular momentum and spin is not valid generally, but rather that mixed theories can produce the results which might violate this law). In present paper, an additional explanation following our Corollary is given to why the calculation of the stopping power in the fully quantized theory gives better results than those that were obtained in mixed theories, which further confirms the predictions of our Corollary. [Projekat Ministarstva nauke Republike Srbije, br. 171021: The experimental and theoretical research in radiation physics and radioecology]