A propagating disturbance, such as an electromagnetic wave or a sound wave, impinging upon a boundary or interface between two different media is termed an incoming wave. This initial wave, originating from a source and traveling towards a target, represents the energy that will interact with the medium it encounters. For example, when light encounters a glass surface, the light traveling from the source towards the glass is this type of wave.
Understanding the characteristics of this initial disturbance is critical in numerous fields. In physics and engineering, its properties, including amplitude, frequency, and direction, are essential for predicting the behavior of the wave after interaction. These parameters dictate phenomena like reflection, refraction, transmission, and diffraction. Furthermore, accurate analysis of these waves contributes to advancements in areas ranging from telecommunications to medical imaging, and seismic analysis.