Unit 6.2 Refraction

• • when light passes from one medium to another
  • it changes speed due to different densities of the medium
  • change of speed causes the light to change direction too
  • medium: material that light passes through

  Hence...

  • the change of direction of light on passing from one medium to another medium is due to the change in speed
• Why will light be bent?

  • light passes a medium at an angle
  • one side of the beam will reach the medium first compared to the other side
  • the side of the beam that hits the glass first will slow down while the other side is at current speed until it hits the medium
  • so instead of becoming a straight line, the ray will be bent once in contact with the glass
• Light passing from air into water/glass

  • when light passes from a less dense medium (air) into a denser medium (water/glass) it slows down
  • thus, the light is bent towards the normal
  • giving i > r
• Light passing from water/glass into air

  • when light passes from a denser medium into a less dense medium, it speeds up
  • thus, the light is bent away from the normal
  • giving i < r