International General Certificate of Secondary Education (IGCSE) Physics Practice Exam

When waves encounter a boundary between two different media, the primary phenomena observed are reflection and refraction.

Reflection occurs when a wave strikes a boundary and bounces back into the original medium. This is common with light waves reflecting off surfaces like mirrors or water surfaces.

Refraction happens when a wave enters a new medium at an angle, causing it to change speed and, consequently, its direction. This bending of the wave can be seen when light passes from air into water or from one type of glass into another.

Both of these processes demonstrate how waves interact with different materials, an essential concept in understanding wave behavior in physics. The other options do not accurately explain this interaction; waves do not simply disappear or change direction without continuing their propagation, and there is invariably some change at the boundary. Thus, the ability of waves to be reflected or refracted at boundaries reinforces the understanding of wave behavior in different media.