5.2 - Reflection

• What is the focus of today's video?

  Reflection of waves off a boundary
• What are the two types of reflection discussed?

  Specular and diffuse reflection
• What happens when a wave arrives at a boundary?

  It can be absorbed, transmitted, or reflected
• What is the first option when a wave meets a boundary?

  The wave might be absorbed
• Waves are ________ reflected.


  sometimes
• What occurs when a wave is absorbed by a material?

  Energy is transferred to the material's energy stores
• What is the second option when a wave meets a boundary?

  The wave could be transmitted
• What happens during transmission of a wave?

  The wave enters the material and continues traveling
• What is the third option when a wave meets a boundary?

  The wave could be reflected off the surface
• What determines which of the three options occurs when a wave meets a boundary?

  The wavelength of the wave and material properties
• What is a ray diagram used for?

  To show reflection taking place
• What is the simple rule for reflection?

  The angle of incidence equals the angle of reflection
• How do you start drawing a ray diagram?

  Draw the boundary between two materials
• What does the normal line represent in a ray diagram?

  A dashed line perpendicular to the surface
• How do you measure the angle of incidence?

  Measure the angle between the incoming ray and the normal
• What is the point where the incoming ray touches the boundary called?

  The point of incidence
• What type of reflection occurs with smooth materials like mirrors?

  Specular reflection
• What is the result of specular reflection?

  It gives a clear image
• What type of surface causes diffuse reflection?

  A relatively rough surface
• Why can't you see your reflection in paper?

  Because it undergoes diffuse reflection
• What happens to the normals on a rough surface?

  They point in different directions
• What is true for both specular and diffuse reflection?

  The angle of incidence equals the angle of reflection
• Depending on the conditions, when light hits a material it can be:

  • Transmitted 
  • Absorbed 
  • Reflected 
• In reflection, the angle of incidence is always ________ the angle of reflection.

  equal to
• Incoming ray: A

  Point of incidence: F

  Angle of incidence: D

  Reflected ray: C

  Normal: B

  Angle of reflection: E

  
• Specular reflection occurs on surfaces where the boundary is flat.
• What type of image will specular reflection produce?

  A clear image
• Diffuse reflection occurs on materials where the surface is bumpy (uneven).
• This means you _________ usually see your reflection in these materials.

  cannot