1. WAVES: INTRODUCTION A fixed boundary (one that cannot move) limits the amplitude to zero! Note how the wave returns…

2. WAVES: INTRODUCTION An open (or free) boundary is one that doesn’t limit the amplitude – it can reach its max value Note how the wave returns here…

3. WAVES: INTRODUCTION

4. Interference of Waves Or…When Waves Collide!

5. WAVES: INTRODUCTION When waves meet they can “interfere” in a positive way…their amplitudes ADD: it’s called “Constructive Interference”

6. WAVES: INTRODUCTION Or they can “interfere” in a negative way: their amplitudes will SUBTRACT: it’s called “Destructive Interference”

7. WAVES: INTRODUCTION Here’s an example of both events happening when these two wave sets cross. They might be sound waves, they might be radio waves…

8. WAVES: INTRODUCTION Interference and Boundary effects For a string fixed at both ends:

9. WAVES: INTRODUCTION Other examples of “boundaries” From a light to a heavy medium: From a heavy to a light medium: