Refractionof waves

Starter

Copy and complete the diagram, labelling fully.

Light wave

Air

Glass

Learning Objectives

• Know what refraction and dispersion are.

• Know why refraction occurs.• Know how to calculate the refractive

index.

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)

Answer to starter1. 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

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?

Why does refraction happen?

Now lets have a look at worksheet P5g2 (on next 2 slides)

Also look at page 201 – old course

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.

Tasks

• Foundation: read “refraction and dispersion” on page 212-13 (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.

Learning Objectives

• Know what refraction and dispersion are.

• Know why refraction occurs.• Know how to calculate the refractive

index.

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)

Plenary

• Foundation: worksheet P5g1 – old course

• Higher: worksheet P5g4 – old course