2. Reflection at an Angle Normal Ray of light, or “ray” of sound at an angle to reflector Virtual Ray Incident angle reflected angle mirror Think about this next time you play pool Normal is drawn perpendicular to boundary

3. Refraction: bending of a wavefront at a boundary between two media, due to the change in velocity Refraction water air Incoming wave Slower velocity

4. Helpful Analogy: Marching Band Firm Ground Muddy Mess

5. Helpful Analogy: wheel on an axel Firm Ground Muddy Mess

6. Diffraction If a sound wave hits a door opening, the sound will bend/spread Spreading will be the most for… Small opening relative to the wavelength. So… smaller the opening, the more diffaction and the longer the wavelength the more diffraction.

7. Diffraction d Larger barrier with smaller gaps relative to the wavelength. So… larger the barrier = smaller gaps, = more diffaction and again, the longer the wavelength the more diffraction. Spreading will be the most for…

8. http://rt210.sl.psu.edu/phys_anim/waves/indexer_waves.html http://paws.kettering.edu/~drussell/Demos/superposition/superposition.html INTERFERENCE OF WAVES The principle of superposition may be applied to waves whenever two (or more) waves are travelling through the same medium at the same time. The waves pass through each other without being disturbed. Constructive interference: Point where two waves meet in phase to produce a wave of larger amplitude. Destructive interference: Point where two waves meet out of phase in order to produce waves of smaller amplitude.