Answers to Extra Questions for
Module 3 -- Absorption, Reflection, Refraction;
Angles of Incidence, Refraction and Deviation.
  1. DEFINE and give an example, where appropriate  You look these up.
    1. absorption
    2. deviation [angle of]
    3. diffuse reflection
    4. incidence [angle of]
    5. reflection
    6. refraction
    7. refraction [angle of]
    8. specular reflection

      9.  
  2. Label the diagram:

    3.  
    1. incident ray

    2. normal to the surface [for the first refraction]

      3.  
    3. angle of incidence [for the first refraction]

      4.  
    4. angle of deviation [for the first refraction]

      5.  
    5. angle of refraction [for the first refraction]

      6.  
    6. angle of incidence [for the second refraction]

      7.  
    7. normal to the surface [for the second refraction]

      8.  
    8. angle of refraction [for the second refraction]

      9.  
    9. emergent ray

      10.  
    10. where the ray would have been if the sheet of glass were not there

      11.  
    11. displacement of the ray from the original path

      12.  

       
       
       
       
       

  3. OK, once again:
    1. Why is my red pencil red?  reflects red rays back toward your eye, absorbs all other rays.
    2. Why is the blacktop black?  does not reflect any rays back toward your eye;  absorbs them all.
    3. If you shine a light beam through your green sunglass lenses, why will the light coming out be green?  The green rays are refracted through the lens, and all other color rays are absorbed by the pigments in the lens material.
       
  4. When a ray of light travels from air into water, which is denser than air, what happens to the ray of light if
    1. the ray is perpendicular to the surface  It slows down but does not change direction.  It is not deviated or displaced.
    2. the ray is not perpendicular to the surface  It slows down and changes direction toward the normal.  It is deviated from it's original path.

     
  5. When a ray of light travels from water into air, which is rarer than water, what happens to the ray of light if
    1. the ray is perpendicular to the surface  It speeds up but does not change direction.  It is not deviated or displaced.
    2. the ray is not perpendicular to the surface  It speeds up and changes direction away from the normal.  It is deviated from it's original path.

     
  6. What does critical angle mean?  A ray leaving a denser material for a rarer material that is at an angle to the normal that results in it traveling parallel to the surface of the material.  If the angle of incidence is greater than the critical angle the ray will reflect inside the material and will not exit into the rarer material.

    7.  

     
     
     
     
     

  7. If a ray travels from air to water with an angle of incidence of 15 degrees and an angle of refraction of 11 degrees, how much was it deviated?  Draw what happened.
        8. i = 15
        r = 11
        d = ?
        i = r + d
        15 = 11 + d
        d = 15 - 11
        d = 4

     
     
  8. If the ray leaves the water traveling into air with an angle of incidence of 20 degrees and it is deviated by -7 degrees, what was the angle of refraction?  Draw what happened.
        9. i = 20
        r = ?
        d = -7
        i = r + d
        20 = r + (-7)
        r - 7 = 20
        r = 20 + 7
        r = 27

 
 


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