Waves

• Waves


  Transfer energy without transferring matter
• Waves


  • Water waves at the beach
  • Electromagnetic waves
• Wave


  • Crests (tall bits)
  • Troughs (low bits)
  • Amplitude (height from rest position)
  • Wavelength (distance between crests)
• Frequency


  Number of wavelengths that pass a point per second
• Frequency


  Calculated by dividing velocity by wavelength
• Units


  • Frequency (Hertz)
  • Wavelength (Meters)
  • Velocity (Meters per second)
• Types of waves


  • Transverse waves
  • Longitudinal waves
• Transverse waves


  • Vibrations go up and down
• Longitudinal waves


  • Vibrations go left and right
  • Have compressions (vibrations close together)
  • Have rarefactions (vibrations far apart)
• Transverse waves


  • Light waves
  • Water waves at beach
  • Waves on electromagnetic spectrum
• Longitudinal waves


  • Sound waves
  • P-waves (seismic waves from earthquakes)
• Sound wave pitch


  • High pitch = short wavelengths
  • Low pitch = long wavelengths
• Wave transmission


  • Passing through material
  • Absorbed by material
  • Reflected off material
• Refraction


  1. Wave changes speed and direction when entering new material

  2. Frequency does not change
• Refraction


  • Angle of incidence
  • Angle of refraction
• Reflection


  • Wave bounces off material
  • Angle of incidence = Angle of reflection
• Types of reflection


  • Specular (flat surface, uniform reflection)
  • Diffuse (rough surface, scattered reflection)
• Reflection uses


  • Ultrasound (high pitched sound waves reflected)
• Electromagnetic spectrum


  • Range of all transverse waves
  • Visible light is a small part
  • Colours combine to form white light
• Object colour


  Reflects the colour it appears, absorbs other colours
• Types of objects


  • Black (absorbs all light)
  • Transparent/translucent (allows light to pass through)
• Lenses


  • Convergent (bring light to a focus)
  • Divergent (spread light out)
• This video helps with physics and vision