Unit 4 – Waves

• Requires a medium (substance)

  Mechanical Waves
• No medium required

  Electromagnetic Waves
• Example of Mechanical Waves

  • Water
  • Sound
  • Seismic
• Example of Electromagnetic Waves

  • Light
  • UV
• The wave vibrates/oscillates perpendicular to the direction the wave travels

  Transverse
• The wave oscillates parallel to the direction of motion

  Longitudinal
• A measure of how often an events occurs?

  Frequency
• A measure of how long it takes for a complete oscillation

  Period
• Number of occurrence over time

  Frequency
• T=1/f or f=1/t

  Period
• #/s

  Frequency
• Distance form equilibrium to top of wave

  Amplitude
• Waves are a method of moving energy from one location to another
• V=fƛ

  Wave Equation
• When two waves interact they create a resultant wave whose displacement is equal to the sum of the original waves displacement

  Superposition
• Higher frequency = Higher Pitch

  Lower Frequency = Lower Pitch

  Frequency (Pitch)
• For a particular frequency the larger the amplitude the louder the sound and the more energy it carries

  Amplitude (Volume, Loudness)
• Speed of sound in air is most affected by temperature
• Vs=331 + 0.6T

  Speed of Sound
• Reflection of a sound wave

  Echoes
• An object vibrating at one frequency causes another object to vibrate at the same frequency

  Resonance
• What happens when two sounds are played together?

  You hear a "wow-waw-waw" sound
• The difference frequencies interfere with each other, resulting in some low amplitude in the resultant waves

  Beat Frequency
• Angle of Incident = Angle of Reflection

  Reflection
• The bending of a wave due to a change in speed

  Refraction
• 2 (or more) eaves add together to make a wave of greater amplitude

  Constructive Interference
• 2 (or more) waves add together to make a wave of smaller amplitude

  Destructive Interference