Physics- Waves and Sound, Light

• Wave

  An oscillation or vibration that transfers energy from one place to another
• Sound waves help you communicate
• Transverse waves

  • Vibrations (oscillations) move up and down perpendicular (at right angle) to the direction of travel
  • Examples: water ripples, light, on a rope/ slinky, earthquake
• Longitudinal waves


  • The oscillations are parallel to the direction of travel
  • Examples: sound, slinky, earthquake
• Waves transfer energy, not matter
• The direction of oscillation is at 90 degrees
• Amplitude

  Distance from middle to the top/ bottom of the wave
• Frequency

  Number of waves that go past a point per second
• Peak/Crest


  Top of a wave
• Trough


  Bottom of a wave
• Wavelength


  Distance from one point on a wave to the same point on another wave
• Reflection


  Waves bounce off surfaces and barriers
• Incident wave


  The wave that is hitting the barrier
• Reflected wave


  The wave bouncing off
• Soundwave


  A type of longitudinal wave
• Loudness


  The higher the amplitude the louder the sound
• Pitch


  High pitch = high frequency, Low pitch = Low frequency
• Oscilloscope


  Can be used to see sound waves
• How your ear works

  1. Sound waves vibrate and are collected through your ear lobe (pinna) and go through your ear canal to your eardrum which vibrates

  2. The three tiny bones (ossicles) then amplify the sound and the cochlea turns them into electrical signals which are sent to your brain through your auditory nerve so you can hear
• Hearing range


  Human: 20Hz- 20,000 Hz
• Hertz


  Measures frequency
• Loudness


  Measured in decibels
• Loudness levels


  • Right next to speakers at a concert- 160
  • Chainsaw- 100
  • Conversation- 40-50
  • Jet engine- 130
  • Alarm clock- 60
  • Lawnmower- 100
  • Whisper- 20
• Temporary hearing loss


  Can be caused by ear infections and will last 16-48 hours. To treat it, you should have as much silence as possible, possibly take antibiotics and remove blockages
• Echo


  A reflected sound wave
• Calculating distance using echo

  1. Distance (m) = Speed x Time (s)

  2. Time = Distance / Speed

  3. Speed = Distance/ Time

  4. Speed of sound= 340
• Distance= 340 x 0.8=272m, divided by 2 = 136m (It is divided by 2 because we only want the distance to the sea bed)
• Ultrasound


  • Non-invasive and does not expose the patient to radiation
  • Provides images in real time
  • Emits a sound that is inaudible to human ears
• Dolphin echolocation


  • Dolphins have the unique ability to navigate through the dark parts of the ocean using echolocation
  • Echolocation is used to see the world through sound
  • Echolocation interprets the echoes of sound waves by bouncing off nearby objects
  • The soundwaves are picked up in the dolphin's lower jaw and sent to its brain as signals
  • Jaque Eves Gousto discovered echolocation
  • Dolphins emit high frequency sound when echolocating
• Bat echolocation


  • Bats use echolocation
  • The clicks and squeaks emitted by bats are inaudible to human hearing
  • To bats, they are so loud that they turn off their hearing while emitting and then they turn it back on again
• Humans hearing range- 20-20,000Hz
• Ultrasound waves reflect off the surface of the foetus, a machine detects this to build up an image
• Animals such as bats and dolphins also use ultrasound echoes to help them see or locate objects
• The speed of sound is 340 m/s. This means that the sound travels 340 metres in one second. We can use this information to calculate distances using echoes.
• Ultrasound scans can be used to look at unborn babies, tumours and internal injuries.
• The techniques and precision of the measurement equipment might be different.
• Light is a way of transferring energy from one place to another. Light travels much faster than sound and can travel through a vacuum.
• Light is an example of a transverse wave. The speed of light is 300,000,000 m/s.
• Luminous


  Objects that make their own light
• Non-luminous


  Objects that do not make any light and reflect the light from luminous objects