5WACS-1

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Outcomes

  • Pupils can use a raybox.
  • Pupils can construct ray diagrams.

Specification References

  • 3.16 construct ray diagrams to illustrate the formation of a virtual image in a plane mirror

Starter

  • Give pupils one minute to list words they associate with light.

Main Body of Lesson

  • Demonstrate to pupils how a raybox works.
    • It is now standard to tape down a piece of A3 paper to the bench before using a raybox.
  • Have pupils (in pairs) set up a raybox. Walk around the room with semicircular prisms and issue prisms to those pupils who have correctly set up their raybox.
  • Ask pupils to "experiment" with the prisms and the rayboxes, to see if they can create any interesting effects. Have them demonstrate these effects to you.
  • Collect in prisms but not rayboxes.
  • Demonstrate the key features of ray diagrams and reference the similarities/parallels with the rayboxes.
    • Rays of light are always straight lines.
    • Rays of light begin at something.
    • Rays of light have arrowheads to show their direction (you might want to point out here that diagrams wouldn't change if direction reversed therefore the reflection interaction is symmetric with respect to time.)
    • The normal is an imaginary line drawn at right angles to a surface.
  • Demonstrate how to measure angle using a protractor. Yes, I'm serious. A lot of them really don't know how to use a protractor effectively. They have a vague idea, but aren't sure. Use WRK181 to check ability to measure angles.
  • Emphasise the necessity of measuring between ray of light and normal. Angles are never measured between surface and ray. Use WRK182 to practice measuring angle of incidence/reflection.

Plenary

  • Next week on 5-WAC: The Law of Reflection

Additional Information

Resources Required

  • Demonstration raybox
  • Class set of rayboxes
  • Perspex blocks - semicircular prisms only.
  • A3 paper
  • Protractors

Textbook References

Website References

Skills Addressed

Safety/Hazards

Rayboxes get hot avoid touching. When operating in limited light walkways need to be kept clear and pupils should take care when moving around.

Notes