Electromagnetic Waves

• Electromagnetic spectrum


  Entire range of electromagnetic waves
• Electromagnetic waves


  1. Oscillate perpendicular to the direction of energy transfer

  2. Travel at 3 x 10^8 m/s in a vacuum

  3. Travel at different speeds in different mediums

  4. Can lead to refraction
• Types of electromagnetic waves

  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • Ultraviolet
  • X-rays
  • Gamma rays
• Wavelength and frequency


  Inversely related - as one increases, the other decreases
• Wavelength ranges


  • Radio waves: multiple kilometers
  • Gamma rays: less than 0.001 nanometers
• Human eyes can only detect a tiny part of the electromagnetic spectrum, called visible light
• Colours of visible light

  • Red
  • Orange
  • Yellow
  • Green
  • Blue
  • Indigo
  • Violet
• After violet in the spectrum

  Ultraviolet
• Before red in the spectrum

  Infrared
• Ultraviolet, X-rays and gamma rays are ionizing and can cause damage to cells
• Microwaves and radio waves


  Used in communication
• Sources of electromagnetic waves

  1. Radioactive decay (gamma rays)

  2. Electrons dropping energy levels (visible, UV, X-rays)

  3. Molecular vibrations (infrared)
• Electromagnetic waves


  • Can be reflected, absorbed or transmitted when they interact with matter