1. 17.3 Behaviors of Waves Reflection Refraction Diffraction Constructive Interference Destructive Interference Standing Waves

2. Reflection When a wave bounces off a surface that it cannot pass through – Ex. – ball can’t pass through a wall, so it bounces off Reflection does not change the speed or frequency of a wave, but the wave can be flipped upside down – Fixed boundary  reflected wave upside down

3. Refraction The bending of a wave as it enters a new medium at an angle Occurs when a wave enters a medium at an angle – One side of the wave moves more slowly than the other side – Refraction applet Refraction applet – In this case, v = different refractive value for a different medium

4. Diffraction PhET diffraction applet PhET diffraction applet The bending of a wave as it moves around an obstacle or passes through a narrow opening A wave diffracts more if its wavelength is large compared to the size of an opening or obstacle – If wavelength < opening/obstacle, then very little bending – If wavelength > opening/obstacle, then larger bending

5. Interference When 2 or more waves overlap and combine together 2 types of interference – Constructive (leads to increased amplitude) – Destructive (leads to decreased amplitude)

6. Constructive interference When 2 or more waves combine to produce a wave with a larger displacement (amplitude)

7. Destructive Interference When 2 or more waves combine to produce a wave with a smaller displacement (amplitude)

8. Standing Waves A wave that appears to stay in one place – it does not seem to move through the medium Examples – plucked guitar string or elastic cord Node = a stationary point on a standing wave – Complete destructive interference between incoming and reflected waves Antinode = a point where a crest or trough occurs midway between nodes Forms only if a wavelength or a multiple of half a wavelength fits exactly into the length of a vibrating cord.

9. Standing Waves Links to Standing Waves Applets Standing wave created by reflecting off of 1 barrier http://faraday.physics.utoronto.ca/IYearLab/Intros/StandingWav es/Flash/reflect.html http://faraday.physics.utoronto.ca/IYearLab/Intros/StandingWav es/Flash/reflect.html Standing wave created by reflecting off 2 barriers http://faraday.physics.utoronto.ca/IYearLab/Intros/StandingWav es/Flash/standwave.html http://faraday.physics.utoronto.ca/IYearLab/Intros/StandingWav es/Flash/standwave.html