1. Refraction

2. Objectives
To find out how light is reflected at a boundary or interface between 2 different materials.

3. How can we see transparent objects?

4. Reflection & Refraction

5. Refraction

6. Refraction
This diagram shows what happens to light which is reflected by the pencil. The light bends when it leaves the water. Your brain thinks that light always travels in straight lines so the pencil tip seems to be nearer the surface than it really is.

7. Pencil trick
When a pencil is put into a beaker of water it looks ______. This is because the light is __________ as it leaves the water. The light travels _________ in air than water
Choose three of these words to complete the sentences
slower reflected bent faster refracted

8. Pencil trick
When a pencil is put into a beaker of water it looks ______. This is because the light is __________ as it leaves the water. The light travels _________ in air than water
Choose three of these words to complete the sentences
slower reflected bent faster refracted

9. The Kingfisher Refraction Air Water
Refraction of light is the bending of light rays at the interface of dissimilar substances
Air
Water

10. The Kingfisher Refraction Air – lower refractive index
When light is passing from a higher refractive substance into a lower refractive substance the light rays bend away from the perpendicular to the surface.
perpendicular
Air – lower refractive index
Water – higher refractive index

11. The Fish Refraction Air – lower refractive index
When light is passing from a lower refractive substance into a higher refractive substance the light rays bend toward the perpendicular to the surface.
perpendicular
Air – lower refractive index
Water – higher refractive index

12. Glass Window Refraction Air – lower refractive index
Light passing through a transparent material exits at the same angle it enters
Air – lower refractive index
Glass – higher refractive index
Air – lower refractive index

13. Refraction
As the light ray enters the glass block it bends. This is called refraction. The light ray refracts towards the normal as it enters the block and away from the normal as it leaves the glass block. The light is refracted because it travels slower in the glass block than air.

14. Refraction
Application
Lens

15. Lenses

16. Refraction
Refraction of light is the bending of light rays at the interface of dissimilar substances
The angle at which the light is bent depends on the Refractive Indices of the two substances
When light is passing from a higher refractive substance into a lower refractive substance the light rays bend away from the perpendicular to the surface.
When light is passing from a lower refractive substance into a higher refractive substance the light rays bend towards the perpendicular to the surface.

18. Refraction Who to - Key Stage 3
Objective – Light behaviour in different transparent materials. Concept of refraction. How it behaves in different materials. Interpretation of everyday experiences.
What they know – Light reflection, opacity, transparency, basic lenses.
Format – 10 min presentation as introduction to subject with class discussions.
Skills – Problem solving, experimental controls, observation, interpretation, application.
What next – Practical investigation with different materials. Calculation of angles of deflection and Refractive Indices