Waves P4

• How do sound waves travel through a solid?

  Particles vibrate and transfer kinetic energy
• What are the steps in how the human ear works?

  1. Outer ear collects sound
  2. Sound waves vibrate the eardrum
  3. Eardrum vibrations are amplified by ossicles
  4. Hair in cochlea vibrates
  5. Cochlea converts vibrations to electrical signals
  6. Signals are sent to the brain via auditory nerve
  7. Brain interprets signals as sound
• What is the frequency range of human hearing?

  20 Hz - 20 kHz
• What is an ultrasound wave?

  A sound wave greater than 20,000 Hz
• What is sound of frequencies less than 20 Hz called?

  Infrasound
• What natural event causes seismic waves and what types are produced?

  • Earthquakes produce seismic waves
  • Types: P-waves and S-waves
• Are P waves transverse or longitudinal?

  Longitudinal
• Are S waves transverse or longitudinal?

  Transverse
• What is a difference between the mediums that P-waves and S-waves can travel through?

  • P-waves travel through solids and liquids
  • S-waves only travel through solids
• What is the significance of P and S waves?

  They provide evidence of Earth's liquid core
• What technique is used to detect objects in deep water and measure water depth?

  • Echo sounding
  • High frequency sound waves emitted and reflected
  • Time difference and wave speed calculate distances
• How does sonar work?

  • Ultrasound waves reflect off boundaries
  • Echoes are detected
  • Distance = speed x time used to find distance
  • Distance is halved for emitter to boundary
• How does foetal scanning work?

  • Ultrasound wave sent into the body
  • Reflects off organs and tissue
  • Reflected waves produce an image of the foetus
  • Ultrasound is safe and non-damaging
• What is the equation used to calculate wave speed?

  Wave Speed = Frequency x Wavelength
• What are the appropriate units for wave speed, frequency, and wavelength?

  Speed (m/s), Frequency (Hz), Wavelength (m)
• What word describes when a wave bounces off a surface?

  Reflection
• What is the normal in terms of reflection and refraction?

  A vertical imaginary line perpendicular to the boundary
• What occurs when light is reflected off a boundary?

  It bounces off a smooth flat surface
• What is refraction?

  Change in speed of a wave at a boundary
• What occurs when light is refracted at a boundary?

  Light changes speed and direction in the new medium
• What happens to light when it enters a denser material?

  It slows down and bends towards the normal
• What happens to light when it enters a less dense material?

  It speeds up and bends away from the normal
• How can refraction be measured?

  By measuring the angle of incidence and refraction
• What are the effects of absorption of different wavelengths of waves in different mediums?

  Some materials behave differently depending on wavelength
• How does glass behave with visible light and UV light?

  Transmits visible light, reflects UV light
• How do sound waves travel through a solid?

  Particles vibrate and transfer kinetic energy
• What is the relationship between wave speed, frequency, and wavelength?

  • Wave Speed = Frequency x Wavelength
  • Units: Speed (m/s), Frequency (Hz), Wavelength (m)
• What are the key concepts of reflection and refraction?

  • Reflection: Wave bounces off a surface
  • Refraction: Wave changes speed and direction at a boundary
  • Normal: Perpendicular line to the boundary
• How does light behave when entering different mediums?

  • Denser material: Slows down, bends towards normal
  • Less dense material: Speeds up, bends away from normal
• What do waves transfer?

  Energy and information
• What do waves not transfer?

  Matter
• What are the two types of waves?

  Transverse and longitudinal
• What is a transverse wave?

  Oscillations are perpendicular to energy transfer
• What is a longitudinal wave?

  Oscillations are parallel to energy transfer
• What are the two parts of a longitudinal wave called?

  Compressions and rarefactions
• What are the two parts of a transverse wave called?

  Peaks and troughs
• What is a wave’s amplitude?

  Maximum displacement from undisturbed position
• What is wavelength?

  Distance from one wave point to the next
• What is the frequency of a wave?

  Number of waves passing a point each second
• What is the unit used for frequency?

  Hertz, Hz