Reflection of Waves

REFLECTION is what happens when a progressive wave, travelling through one medium, reaches an interface with a second, different medium: part of the wave's energy is sent back into the original medium, with the wave's direction of travel reversed. This section works through three simple demonstrations -- a wave pulse on a string meeting a rigid (fixed) support, the same pulse meeting a freely-sliding ring, and a pulse crossing between a heavy and a light string joined together -- to extract the rule for exactly HOW the wave's phase changes on each kind of reflection, first fo …