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5.2 Waves and their Properties

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Properties of Waves

  • Waves have two main physical properties: amplitude and wavelength
  • The amplitude is the distance from the equilibrium line (the center line) to the crest or to the trough
  • The wavelength is the distance between two crest or two trough.

  • The frequency of a wave is the number of waves that pass a given period.
    • It is often expressed in Hertz or cycles per second
    • It is also directly related to the wavelength of a wave.
      • Longer wavelengths lower frequencies
        Shorter wavelengths higher frequencies

Light Waves

  • The electromagnetic spectrum encompasses all of electromagnetic radiation that occurs in our environment.
  • The visible light spectrum is the only portion of the electromagnetic spectrum that we can see
    • Waves within this spectrum has wavelengths that range from .

  • Other species can detect other portions of the electromagnetic spectrum.

Color Perception

  • Our perception of color is dependent on the wavelength of light
  • Longer wavelengths of light are associated with warmer colors: red, orange, yellow
  • Shorter wavelengths of light are associated with cooler colors: green, blue, violet

Sound Waves

  • We perceive the frequency of a sound wave as its pitch.

    • A high-frequency wave means a high-pitched sound and a low-frequency wave means a low-pitched sound.

  • Humans can hear between .

    • We can easily pick up sounds with frequencies that fall in the middle of this range.
    • Other species can differ in their audible range.

  • We perceive the amplitude of a soundwave as its loudness.

    • A high amplitude sound wave means a louder sound.

  • Loudness is measured in terms of decibels ()

Misplaced \hline\array{c}{ \fn{Sound Intensity Chart}\newline \array{|l|c|}{ \hline \fn{Sound} & \fn{Intensity (in dB)}\newline \hline \fn{Hearing threshold} & 0 \newline \fn{Leaves rustling} & 20 \n \fn{Whisper} & 30 \n \fn{Soft music} & 40 \n \fn{Refrigerator} & 45 \n \fn{Safe, normal conversation} & 60 \n \fn{(Irreversible Damage after 8hr exposure)} & 80 \n \fn{Heavy city traffic} & 85 \n \fn{(Irreversible Damage after 6hr exposure)} & 90 \n \fn{Motorcycle} & 95 \n \fn{(Irreversible Damage after 15min exposure)} & 100 \n \fn{Earbud Maximum Volume} & 105 \n \fn{Risk of Hearing Loss} & 110 \n \fn{Rock Concert} & 120 \n \fn{Pain Threshold/Jet Takeoff} & 120\n \fn{Immediate Permanent Damage} & 140\n \fn{Firearms} & 150 \n \hline } }

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