9 - Reflection and Refraction

• Investigate the reflection of light by different types of surfaces part 1:

  1. Use a ray box, lens and a slit to produce a narrow ray of light
  2. Draw a straight line down the centre of an A3 piece of paper using a ruler
  3. Use a protractor to draw a line at right angles labelled N (normal)
  4. Place a glass block against the first line so that the normal is near the centre of the block
  5. Draw around the glass block
  6. Turn out all of the lights in the room

  
• part 2:

  7. Use the ray box to direct a ray of light so it hits the block at the normal (incident ray)

  8. Adjust the ray box to change the angle of incidence (the angle between the incident ray and the normal)

  9. At a certain angle, we can see a ray reflect from the surface of the block

  10. We can also see another ray leaving the block from the opposite side (transmitted ray)

  11. Mark the path of the incident ray and the reflected ray with crosses

  12. Mark the path of the transmitted ray

  13. Turn on the room lights and switch off the ray box

  
• part 3:

  14. Remove the glass block

  15. Draw in both the incident ray and the reflected ray

  16. Draw in the transmitted ray so it meets the position of the block

  17. Draw a line to show the path of the transmitted ray through the glass block

  18. Use a protractor to measure the angle of incidence, the angle of reflection and the angle of refraction (the angle between the normal and the path of the transmitted ray through the block)

  19. Repeat the entire experiment, instead using a block made from a different material e.g. plastic such as perspex

  
• In this experiment, you should find out that the angle of incidence and reflection are the same for both glass and perspex (plastic). This is because the angles of incidence and reflection do not depend on the material, however the angle of refraction will be different with perspex than with glass because the angle of refraction is different for different materials