The bending of electromagnetic (EM) waves caused by a change in the density of the medium through which the waves are passing is referred to as:

Refraction refers to the bending of electromagnetic (EM) waves as they pass from one medium to another, resulting from a change in the density of the medium. This phenomenon occurs because electromagnetic waves travel at different speeds in different materials. When EM waves encounter a boundary between two media with differing densities, their speed changes, leading to a change in direction.

The degree to which the waves bend is determined by Snell's Law, which relates the angles of incidence and refraction to the indices of refraction of the respective media. This principle is crucial across various applications, including optics, telecommunications, and radar systems, as it influences how signals propagate through different environments.

Understanding refraction is vital for designing systems that utilize electromagnetic waves, as it impacts how signals are transmitted and received, leading to better performance and communication reliability.