Physical Science - Chapter 21 

Electromagnetic Energy

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

21B The Electromagnetic Spectrum

• %%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

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