The scattering of the rays of an ultrasonic beam due to reflection from a highly irregular surface is called:

• A. Dispersion
• B. Angulation
• C. Refraction
• D. Rarefaction

Answer: (A)

When a surface is highly irregular, each tiny facet on the surface reflects part of the ultrasound in different directions instead of sending a single, strong reflected beam back to the probe. The result is that the energy is spread out rather than concentrated along one path. This spreading or redistribution of energy is described as dispersion in this context, reflecting the way the ultrasound scatters off a rough surface. The other terms don’t fit this situation: angulation is about steering the beam by changing orientation, refraction is the bending of the beam when moving between media, and rarefaction is simply a low-pressure portion of the wave. So dispersion best captures the effect of scattering from a highly irregular surface.