sound and light

• when is sound produced

  whenever an object vibrates
• Sound travels through solid liquids or gases as sound waves
• how is sound produced from string instruments

  When the strings of the instruments are plucked they vibrate and produce sound
• How is sound produced from percussion instruments

  When the skin of the instrument is hit a sound is vibrated
• How is sound produce from wind instruments

  When the instrument is filled with air in the column of it, It vibrates when is blown
• longitudinal wave


  Sound is a longitudinal wave.The particles vibrate back and forth in the direction of a wave
• rarefaction


  The section where air particles are spread apart
• wavelength


  The distance between one point to the next identical point on the wave
• compression


  The section where air particles are pushed together
• Where does sound travel fastest and why

  Sound travels faster in solids than any other material.As the particles are closer together which allows vibrations to be passed more easily
• vacuum


  A place where there are no particles
• examples of vacuums

  • space
  • sound proof double glazing windows
• What are oscilloscopes used for


  Observing sound waves
• amplitude


  The height of the wave from the middle of the wave
• frequency (pitch)


  How many waves past a point in a second (Hertz Hz)
• What is the human hearing range

  20-20,000 Hz
• Ultrasounds


  Sounds above 20,000 Hz
• echo


  When a sound wave bounces off of a surface back to the listener
• echolocation


  The process of locating distant or invisible objects by using sound waves reflected back from surfaces
• speed equation


  used to measure the speed of sound

  speed = distance (m) ÷ time (s)
• How does the ear hear?

  1. Sound waves are collected by the earlobe or pinna
  2. The waves travel along the ear canal
  3. The waves make the ear drum vibrate
  4. Three small bones carries vibrations to the cochlea
  5. The cochlea turns these into electrical signals
  6. The auditory nerve takes the signals to the brain
• Temporary hearing loss


  Can be caused by very loud noises over a long period of time or ear infections
• Permanent hearing loss


  And be present at birth or if the auditory nerve gets damaged or diseased
• Sound


  An unwanted sound measured in decibels (dB)
• How loud does sound have to be to cause deafness

  • Sounds at ninety decibels can cause partial deafness
  • Sounds louder than one hundred and twenty decibels can burst or tear the eardrum
• ultrasounds


  Sounds above. 20,000 hertz are too high for us to hear.These are called ultrasounds
• uses of ultrasonic waves

  • Bats use ultrasound to locate prey and navigate
  • Dolphins use ultrasound to communicate with others miles away
  • Prenatal scanning
  • Breaking up kidney stones
  • sonar
  • Checking underground pipes
  • uktrasonic cleaning of jewelry and teeth
• Light


  Travels extremely fast in straight lines
• Luminous


  An object that makes its own light
• Non-luminous


  An object that does not make its own light
• Opaque


  Objects that do not let any light go through it
• Transparent


  Objevts that let all light through
• Translucent


  Objects that allow some light through
• Shadows


  Places where light is blocked
• Reflection


  When light bounces off of a surface
• Reflection of a light wave

  
• Law of reflection


  Angle of incidence = angle of reflection
• Lateral inversion


  When left befomrs right and right becomes left in reflection
• Refraction


  When light changes speed and hends as it pqsses from one medium (material) to another
• Lenses


  Curved pieces of glass of transparent plastic thate designed to refract light in particular ways