P6

• • waves transfer energy form one place to another without transferring matter
  • waves travel through medium, particles of the medium oscillate and transfer energy
• amplitude: the maximum displacement of a point of one wave to another
• wavelength: the distance of one entire oscillation
• frequency: the number of complete waves passing a certain point per second
• time period: time it takes one complete oscillation
• wave speed = frequency x wavelength
• all waves are transverse or longitudinal:

  • transverse waves: the oscillation are perpendicular to the direction of energy transfer
  • longitudinal waves: the oscillation is parallel to the direction of energy transfer
• all electromagnetic waves are transverse
• all waves can be absorbed, transmitted or reflected:

  • when waves arrive at a boundary between two different materials it can either be absorbed, transmitted or reflected
• • absorbed: transfers energy to the materials energy store
  • transmitted: the wave enter the material, but carries on travelling
  • reflected: never enter the material
• what happens when a wave arrives at a boundary depends on:

  • the wavelength of the wave
  • properties of the material
• Law of reflection: angle of incidence = angle of reflection

  
• specular reflection: happens when a wave is reflected in a single direction by a smooth surface

  diffuse reflection: happens when a wave is reflected by a rough surface, reflected rays are scatters have different normal
• refraction: when waves change direction as they pass from one medium to another
• how much an object is refracted:

  • how much the wave speed slows down or speeds up, which depends on the density of the material
  • the higher the density of a material = slower the wave travels
  • if wave enters a more dense medium it will bend towards the normal
• • if a wave enter a less dense material the wave speed with speed up, meaning it will bend away from the normal
  • the wavelength of a wave changes when it is refracted but not its frequency
• • all electromagnetic waves travel at the same speed in a vacuum: 3 x 10^8 m/s
  • in different mediums, travels at different speed