What principle explains the behavior of X-rays as they pass through matter?

The principle that explains the behavior of X-rays as they pass through matter is indeed the photoelectric effect. This phenomenon involves the interaction between X-rays and the atoms in the material they encounter. When X-rays pass through a substance, they can be absorbed by the atoms, causing the ejection of electrons from those atoms. The degree of this interaction depends on the energy of the X-rays and the composition of the material.

In the context of radiologic imaging, understanding the photoelectric effect is crucial because it helps determine how much radiation is absorbed or transmitted based on the density and atomic number of the tissues involved. For instance, denser tissues, like bone, will absorb more X-rays due to the photoelectric effect than less dense tissues, such as muscle or fat, leading to the contrast necessary for medical imaging.

The other choices do not correctly describe the interaction of X-rays with matter in this context. The Doppler effect relates to wave frequency shifts in relation to an observer's motion and is not applicable to X-ray interactions. The law of reflection concerns how light or waves bounce off surfaces, which does not pertain to the absorption or transmission of X-rays in medical imaging. The principle of superposition deals with the combination of waves and is not