4/6/09

Post date: Apr 06, 2009 11:47:16 AM

Bell Ringer: Why can you hear someone who is around a corner from you?

• • Wave speed

    • Depends on what type of wave

    • Depends on properties of the medium

      • molecules that are closer together transmit waves faster

      • Gases - farthest apart, so slowest waves

      • Liquids - closer together, so faster waves

      • Solids - closest together, so fastest waves (try tapping on desk with ear pressed to it... do you hear it better with your ear to the table or the one that's not on the table?)

    • Light has definite speed = 300,000,000 m/s in a vaccuum.

  • Doppler effect

    • Waves move at a certain speed, regardless of how fast the wave source is moving

      • Waves ahead of source get squeezed together for a higher pitch, waves behind get spread apart for lower pitch

    • Page 522 for picture and explanation

    • Example - Moving chimes

    • These animations will help you visualize this

  • Wave Interactions

    • Reflection - waves bound off a surface at the same angle as they hit it at

    • Diffraction - waves bend around the edge of an object

    • Refraction - waves change speed and get bent as the go through a surface

    • Interference - waves combine with each other when they occupy the same space, and make a bigger or smaller wave than the original

  • Write a 1-page summary of these behaviors which includes a description and examples of each