Physical Science - Chapter 21 

Electromagnetic Energy

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21A Electromagnetic Waves

  • %%Electromagnetic Wave%%: a disruption in an electromagnet field that carries energy, even through the vacuum of space
  • %%Photon%%: a wave bundle, or particle, of electromagnetic energy

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21B The Electromagnetic Spectrum

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  • %%Electromagnetic Spectrum%%: the entire range of all electromagnetic wave s
Electromagnetic Spectrum
  • %%Radio Wave%%: the longest and lowest energy type of electromagnet wave   * Frequency: 3 Hz to 300 GHz   * Wavelengths: 100 000 km to 1 mm   * Uses: navigation, communication
  • %%Microwave%%: a wave from the upper end of the radio wave band   * Frequency: 300 MHz to 300 GHz   * Wavelengths: 1 m to 1 mm   * Uses: navigation, communication, astronomy, cooking
  • %%Visible Light%%: electromagnetic waves that humans can see   * Frequency: 430 THz to 790 THz   * Wavelengths: 700 nm to 380 nm
  • %%Ultraviolet Wave%%: an electromagnet wave that is just beyond (more energetic than) violet visible light   * Frequency: 790 THz to 30 PHz   * Wavelengths: 380 nm to 10 nm   * Uses: medical treatment, dentistry, killing bacteria
  • %%X-ray%%: photograph taken with x-ray   * Frequency: 30 PHz to 30 EHz   * Wavelength: 10 nm to 10 pm   * Uses: medical imagery, transportation security, nondestructive inspection
  • %%Gamma Ray%%: a high-energy photon that is emitted from a nucleus when a radioactive isotope experiences gamma decay   * Frequency: above 30EHz   * Wavelengths: 10 pm down to 1 fm   * Uses: medical treatment, astronomy

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Using Electromagnetic Waves
  • %%Amplitude Modulation%%: the process of putting information into a radio wave by changing, or modulating, the amplitude of the wave
  • %%Frequency Modulation%%: the process of putting information into a radio wave by changing, or modulating, the frequency of the wave

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