EM waves & light

• • When EM waves move from one medium to another the waves might be:
  • Transmitted
  • Absorbed
  • Reflected
  • Refracted
• What happens to waves when move to a different medium?

  A) Reflection

  B) Absorption

  C) Transmission

  
• The material interacts differently with different parts of EM spectrum because of the difference in wavelength

  Whilst some wavelengths might be transmitted, others might be reflected, refracted or absorbed
• • Which of the interactions happen depends on:
  • The wavelength of the waves
  • The material the wave is travelling through
  • For example, glass will:
  • Transmit and/or refract visible light
  • Absorb UV radiation
  • Reflect IR radiation
• Refraction of EM Waves

  • Some effects, for example, refraction, are due to the difference in velocity of the waves in different substances
  • Although all electromagnetic waves travel at the same speed in a vacuum, when they encounter certain materials (water, glass, oil) they will slow down
  • How much they slow down depends on the material
  • This slowing of electromagnetic waves causes them to refract
  • A simple example of this is the refraction of visible light when it enters (or leaves) a glass block, although other electromagnetic waves can also refract
• Rarefaction of light:

  A) Convex lens

  B) Concave lens