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Year 9 Physics - Sound and Light

The Doppler Effect and Sound Intro

  • pitch corresponds to frequency, so we can hear 20 - 20,000 Hz
  • too high to hear are ultrasounds
  • some high or loud sounds can be damaging to our ears
  • we use decibels to measure noise, which are logarithmic
  • the closer the source, the higher the pitch - the further away the source, the lower the pitch
  • this is because the waves emitted before catch up with the sound and increase the frequency of the new waves being emitted

Light Intro

  • light is a type of energy that travels in waves

  • any time of energy given off by objects as waves or particles is called radiation, so light is a type of radiation

  • light is the only electromagnetic radiation humans can see

  • the full range of electromagnetic radiation is called the electromagnetic spectrum

  • all electromagnetic waves travel at the speed of light

  • electromagnetic waves vary due to their wavelength, as this relates to the amount of energy transferred

    short wavelength - high energy

    long wavelength - low energy

  • EMR - shows wave-like properties as it travels through space, and moves in a straight line

  • electromagnetic radiation varies both relative to frequency and wavelength

X-Ray

  • shorter wavelength, higher energy
  • travels through materials differently - can be used for medical analysis

Microwave

  • longer wavelength and lower energy
  • absorbed by certain materials, such as food, which in turn heats it up