CHAPTER 6: WAVES II

Waves are all around us—sound, light, water waves, and even matter itself exhibits wave-like properties. This chapter delves into the fundamental behaviors common to all waves: how they reflect, bend, spread, and interfere with each other. We also distinguish between waves that travel (progressive) and waves that appear to stand still (stationary). Master these concepts, and you understand the language of the universe.

6.1 PROPERTIES OF WAVES

All waves—whether mechanical or electromagnetic, transverse or longitudinal—exhibit certain characteristic behaviors. Understanding these is key to predicting how waves will interact with their environment.

6.1.1 Reflection

Reflection occurs when a wave bounces off a surface, changing direction but remaining in the same medium.

• Law of Reflection: For all waves, the angle of incidence equals the angle of reflection. (∠i = ∠r). Both angles are measured from the normal (a line perpendicular to the reflecting surface).
• Examples:
  • Light: Mirrors, still water surfaces.
  • Sound: Echoes.
  • Water waves: Waves bouncing off a harbour wall.
• Wavefront Representation: Straight wavefronts reflect as straight wavefronts. Circular wavefronts reflect as circular wavefronts. The reflected wave appears to come from a virtual image behind the reflector.

6.1.2