Sound and Light Quiz

• Sound


  Vibrations caused by moving objects travelling through air, which we hear
• Sound waves


  • Compressional waves formed when vibrating objects collide with air molecules
  • Speed depends on temperature and state of medium
  • Travel faster in solids and liquids than gases
• Parts of the ear

  • Concha
  • Temporal bone
  • Helix
  • Tragus
  • Vestibular nerve
  • External acoustic meatus
  • Cochlear nerve
  • Cartilage
  • Tympanic membrane (eardrum)
  • Tympanic cavity
  • Eustachian tube
  • Auricular lobule
• How we hear sound


  1. Outer ear catches sound waves

  2. Sound waves travel to eardrum and vibrate it

  3. Sound amplified by 3 bones in middle ear

  4. Inner ear (cochlea) vibrates, sending auditory nerve impulses to brain

  5. Brain's cerebral cortex interprets impulses
• Loudness


  Human perception of sound intensity, measured in decibels
• As sound intensity increases

  Loudness increases
• Pitch


  How high or low a sound seems, related to sound wave frequency
• Bats can hear much higher sounds than humans and use sound to navigate dark caves
• Music


  Sounds deliberately used in a regular pattern
• Musical instruments


  • Vibrate at natural frequencies called overtones, which produce the instrument's distinct sound quality
  • Use resonators (hollow chambers) to amplify sound
• Resonator


  Hollow chamber that amplifies sound when the air inside vibrates
• Engineers who study acoustics design concert halls to maximize sound quality and reflection of sound waves
• SONAR


  System that uses reflection of underwater sound waves to detect objects
• Dolphins, bats, and other animals use echolocation to navigate and search for food
• Ultrasound uses high-frequency sound waves to produce images of the human body
• Transparent


  Allows all light to pass through
• Translucent


  Allows some light to pass through
• Opaque


  Allows no light to pass through
• Reflection


  Light wave strikes an object and bounces off
• Law of reflection


  Angle of incidence equals angle of reflection
• Regular reflection


  Reflection on a smooth surface
• Diffuse reflection


  Reflection on a rough surface
• Refraction


  Light wave bends when passing from one medium to another
• Index of refraction


  Indicates how much a material reduces the speed of light
• Prism separates light into colors due to refraction, with colors appearing in the same order: red, orange, yellow, green, blue, indigo, violet
• Light refracted through air layers of different densities can result in mirages
• Speed of light(C) = 3 x 10^8 m/s
• Wavelength is measured in meters (m)
• Sound intensity is measured in decibels(dB)
• Loudness is the human perception of sound intensity
• Pitch refers to how high or low a sound seems when it's related to the frequency of a sound wave
• The speed of sound depends on temperature, with warmer temperatures causing faster speeds.
• Engineers who study acoustics study the properties of sound
• Humans can tolerate around 120dB of sound intensity before pain.
• High frequency waves produce a high pitched sound and are used for radar and ultrasound
• C(speed of light)=f(frequency) x lambda(wavelength)
• T(period)= 1/f(frequency)
• A light wave has a frequency of 300HZ. What is its wavelength?

  λ=100000m
• Light waves are electromagnetic, and sound waves are compressional mechanical waves.
• v=λf

  T=1/f

  f=1/T

  d=vt

  λ=v/f

  f=v/λ

  c=3(×)10^8

  c=λv

  c=fλ

  λ=c/f

  f=c/λ