waves

• waves transfer energy from one place to another ( don't transfer matter)
• speed of wave = frequency x wavelength
• transverse waves - oscillations are perpendicular to all energy transfer and all EM waves are transverse
• longitudinal waves - oscillations are parallel to the direction of energy transfer, some waves are compressed and spread out
• The amplitude of a wave is the maximum displacement of a point on a wave from its undisturbed position
• the frequency of a wave is the number of waves passing a point each second
• period(s) = 1/frequency(Hz)
• sound waves are a type of longitudinal wave that travels through a medium
• sound waves need particles to be transmitted
• Sound travels faster in solids than in liquids or gases
• in solids the particles are densely packed
• sound waves cannot travel through a vacuum because there are no particles
• as sound waves pass through different mediums the frequency does not change
• as the wave speed increases the wavelength gets longer
• Velocity, frequency and wavelength in transmission of sound waves

  • when sound waves go from one medium to another, the frequency stays the same
  • velocity changes due to the difference in particle density
• waves can be reflected at a boundary between two different materials
• waves can be absorbed or transmitted at the boundary between two materials
• Ray diagram

  
• angle of incidence = angle of reflection
• sound waves can travel through solids causing vibrations in the solid
• within the ear

  • sound waves cause the ear drum and other parts to vibrate which causes the sensation of sound
  • the conversion of sound waves to vibrations of solids works over a limited frequency range
  • which restricts the limit of human hearing
• the range of normal human hearing is 20Hz to 20KHz
• sound waves are a type of longitudinal wave