(The same of electromagnetic waves and mechanical waves)

• When a wave reaches an interface ( boundary) between two materials - for example, air and water - the wave may be:
  • Reflected
  • Refracted
  • Transmitted
  • Absorbed

Reflection:

• Occurs when the wave hits a boundary between two media (an interface) and does not pass through. Instead it returns back into the original material from which it originated.
• Some of the wave may also be absorbed or transmitted
  • Echos are examples of sound waves being reflected off a surface
• Flat surfaces are the most reflective
  • The smoother the surface, the stronger the reflected wave is
• Rough surfaces are the least reflective
  • This is because the light scatters in all directions (example - the walls on the outside of my house, (popcorn paint))
• Opaque surfaces will reflect light which is not absorbed by the material
  • The electrons will absorb the light energy, then reemit it as a reflected wave

Refraction:

• The speed of the wave changed when propagating from one medium to another due to a change in the densities of the two mediums
• Glass and water are both denser than air, so light waves passing from air into them will slow down (and speed up if going from them into air)
• Refraction causes the wave to change its direction
• All waves can be refracted
• Causes change in speed - refer to tution notes (optics ones)

Transmission:

• When a wave passes from one substance to another
  • Wave has to travel from medium 1 to medium 2 and must emerge(come outside) from medium 2
• During transmission some of the waves can be absorbed

Absorption:

• Occurs when energy is transferred from waves into the particles of the substance thro which the wave was propagating through
  • Waves can be completely or partially absorbed