Electromagnetic waves

• EM spectrum:

  Radio waves

  Microwaves

  Infrared

  Visible light

  Ultra Violet

  X-Rays

  Gamma waves
• Going down the EM spectrum the frequency increases and the wavelength decreases.

  So radio waves have the lowest frequency and the highest wavelength.
• Humans can only detect visible light form the EM spectrum.
• Where the EM waves come from;

  • Gamma rays - come from radioactive decay.
  • X-Rays, Ultra Viollet, Visible light - emitted when electrons drop down energy levels.
  • Infrared - bonds holding molecules together vibrate.
• EM waves can be either reflected, absorbed or transmitted.
• EM waves are all transverse waves, so oscillate perpendicular to the direct of energy transfer.
• All EM waves travel as 3 x 10^8 m/s in a vacuum. But when in different mediums they will travel at different speeds.
• Wavelengths in the EM spectrum;

  Radio waves ~ 1 - 100,000 m

  Microwaves ~ 10^-2 m

  Infrared ~ 10^-5 m

  Visible light ~ 10^-7 m

  Ultra Violet ~ 10^-8 m

  X-Rays ~ 10^-10 m

  Gamma waves ~ 10^-15 m
• All EM waves;

  • Move at the speed of light.
  • Can travel through a vacuum.
  • Are transverse waves.