1. Refraction of waves

2. Starter Copy and complete the diagram, labelling fully. Light wave Air
Glass

3. Learning Objectives Know what refraction and dispersion are.
Know why refraction occurs.
Know how to calculate the refractive index.

4. Success criteria
Explain how refraction and dispersion occurs. (Grade C)
Use given equations to calculate refractive indices. (Grade C)
Rearrange given equations to calculate refractive indices (Grade A)

5. Answer to starter
1. What do we call this phenomenon? 2. What can you say about the angle of incidence compared to the angle of refraction when light passes from air to glass?
Normal
Light wave
Air
Glass

6. Dispersion
The amount of refraction depends on the wavelength of light, which is why this happens:
This is called dispersion.
Which has the longest wavelength – red or blue light?
State a rule linking wavelength and amount of refraction.
Can you state the order of the colours of the spectrum?

7. Why does refraction happen?
Also look at page 201 – old course
Now lets have a look at worksheet P5g2 (on next 2 slides)

11. Practical
Practical P5g3 (old course), but half class use glass, half perspex.
Stop at stage 9 on the method. Get results from another group who have used a different block from you.
What can you say about the affect perspex and glass have on wave speed.

12. Tasks
Foundation: read “refraction and dispersion” on page (new book) and then answer questions 3, 4 and 5 on page 213.
Higher: look at “More about refraction” on page 213 (new book). Then answer questions 6 and 7.

13. Learning Objectives Know what refraction and dispersion are.
Know why refraction occurs.
Know how to calculate the refractive index.

14. Success criteria
Explain how refraction and dispersion occurs. (Grade C)
Use given equations to calculate refractive indices. (Grade C)
Rearrange given equations to calculate refractive indices (Grade A)

15. Plenary Foundation: worksheet P5g1 – old course
Higher: worksheet P5g4 – old course