Reflection and Refraction

 When a wave moves from one medium into another (reaches a boundary) ◦ Speed of the wave changes  More dense  slower  less dense  faster ◦ Frequency stays the same ◦ Wavelength changes

 Vocabulary ◦ Incident wave/pulse  The wave traveling towards the boundary ◦ Transmitted wave/pulse  The disturbance that continues moving across the boundary ◦ Reflected wave/pulse  The part of the wave that bounces off the boundary

 Fixed end reflection ◦ The end of the string is held in place ◦ The reflected pulse is inverted

 Free end reflection ◦ The end of the string is free to move up and down ◦ The reflected pulse remains upright

 Moving from a less dense to a more dense medium ◦ The transmitted wave:  Slower  Smaller wavelength ◦ The reflected wave:  Same speed as incident  Same wavelength as incident  inverted

 More dense to less dense ◦ The transmitted wave:  faster  larger wavelength ◦ The reflected wave:  Same speed as incident  Same wavelength as incident  upright

 Refraction ◦ The change of speed causes a wave to bend ◦ Water waves moving from deep to shallow  Waves move slower in shallow water  The wavelength decreases as well

 Fast  slow ◦ Bends towards the normal  Slow  fast ◦ Bends away from the normal  Incident wave is perpendicular to boundary ◦ No refraction (bending)