WAVES

• Waves


  A wave = transfer of energy
• All waves except electromagnetic = medium to travel
• Transverse waves


  The oscillations = perpendicular to the direction of energy transfer
• longitudinal wave


  The oscillations = parallel to the direction of energy transfer
• Amplitude


  How high or low from the middle of the wave
• Wavelength


  the distance between two peaks or troughs in a wave
• Frequency


  It determines the pitch of a sound

  measured in hertz (Hz)
• Waves speed


  Speed of wave measured in metres (m)

  Frequency x wavelength = waves speed
• Waves speed symbol


  v
• Frequency symbol


  f
• symbol for wavelength


  λ

  
• Reflection of wave


  The waves are reflected of a surface at the same angle as they strike.
• Incident ray


  Incoming ray
• Reflected ray


  the light ray that bounces off a surface
• Angle of incidence


  the angle between the incident ray and the normal
• Angle of reflection


  The angle between the reflected ray and the normal
• Angle of incidence = Angle of reflection


  law of reflection
• Refraction in waves


  When waves slow down they change direction

  Frequency = SAME

  Speed = REDUCED

  Wavelength = DIFFERENT

  Direction change depend on material/medium wave travel through
• Diffraction in waves


  the bending of waves around an obstacle
• Superposition/Interference (ADDING)


  2/more waves (move in same way) reinforce

  The 2 waves become 1

  The big wave = greater amplitude
• Superposition/Interference (CANCELING)


  2 waves move opposing direction

  2 waves cancel each other out

  (NO wave anymore)
• Sound waves


  a longitudinal wave consisting of compressions and rarefactions, which travels through a medium
• SPEED OF LIGHT


  300,000 km/s
• Speed of sound


  340 m/s
• Where is sound displayed

  Oscilloscope
• Sound waves need a medium to travel through (proven by the bell jar experiment )

  Sound in the jar could be heard when air is trapped inside

  When air is removed (Vacuum conditions) NO SOUND to be heard
• Parts of the ear

  outer = auditory canal + eardrum

  middle = bones, oval and circular window

  inner = cochlea, auditory nerves

  THE MESSAGE SENT TO THE BRAIN
• Bones of the middle ear

  malleus, incus, stapes (hammer, anvil, stirrup)
• What is noise pollution?

  It is the undesirable levels of noises caused by human activity.
• Sound levels are measured by

  Decibels
• No risk


  0 - 85 dB
• Low risk


  100 - 120 dB
• High risk


  130+ dB
• Hairs in the Ear


  Vibrations of a sound wave convert to energy in hairs in cochlea

  Diff hairs respond to diff frequencies
• Hearing aids


  They have microphones to to detect sound

  It amplifies the frequencies

  Replays in person's ear through speaker