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