Reflection & Refraction

• What is refraction?


  the bending of light
• When does refraction happen to water waves?

  when they cross a boundary between deep and shallow water at a non zero angle to the boundary

  the change of speed at the boundary causes them to change direction
• When does refraction happen to light waves?

  when they travel across a boundary between air and a transparent medium or between two transparent medias

  this is because the speed of light changes at this boundary
• Why is glass more optically dense than air?

  because light travels through it slower than in air
• What effect does the properties of glass on waves have (on light waves)?

  When light enters a more dense medium, it is refracted towards the normal (the angle of refraction is less than the angle of incidence)

  
  

  When light enters a less dense medium, it is refracted away from the normal (the angle of refraction is greater than the angle of incidence)
• What can also occur when waves cross a boundary between 2 materials?

  partial reflection

  the waves that cross the boundary lose energy at the boundary and so have a smaller amplitude than the incident waves
• What is the line perpendicular to the mirror called?

  the normal
• What is the angle of incidence?


  the angle between the incident ray and the normal
• What is the angle of reflection?

  the angle between the reflected ray and the normal
• What is relationship between the angle of incidence and the angle of reflection?

  they are equal
• What is a virtual image?

  an image formed at a place where light rays appear to come from after they have been reflected (or refracted)

  it cannot be projected onto a screen
• What is a real image?

  An image formed by focusing light rays onto a screen.
• What is specular reflection?

  reflection from a smooth surface

  because parallel light rays are reflected in a single direction
• What is diffuse reflection?


  reflection from a rough surface

  because the light is scattered in different directions