4-WAV-02a

Outcomes

• Pupils can state and use the Law of Reflection.
• Pupils can explain refraction as due to a change of speed in different media.
• Pupils can predict the change in direction of a wave due to refraction, including examples using light (including dispersion) and in water, using wave front to explain what is occurring.

Specification References

(SA) 3.14 recall that light waves are transverse waves which can be reflected, refracted and diffraction

(DA) 3.12 recall that light waves are transverse waves which can be reflected and refracted

Starter

• Ask pupils how a mirror works. Link reflection to smoothness of a surface.
• (If you're feeling really brave you could ask why mirrors reflect things right-to-left but not top-to-button.)

Main Body of Lesson

• Use small bulb, radiant heater, two parabolic mirrors, camera and temperature probe to demonstrate that heat waves are reflected just as light waves are.
• Pupils carry out Law of Reflection experiment and discover (for themselves) the Law of Reflection.
• Pupils carry out a "qualitative experiment on Law of Refraction". I think that means that they don't need to know Snell's Law, and you can avoid working with sine functions.

Plenary

• Refraction: Look at the "Spear Fisherman Problem". Why is it that a spear fisherman mustn't aim for the fish itself, but take refraction into account.
• Reflection: Complete corner retroreflector worksheet.

Additional Information

Textbook References

• Pople 7.02 pp. 142-145