- Demonstrate simple situations involving refraction,
eg pencil in beaker of water appears to bend, and the strange views perceived when looking through water,
eg in a swimming pool. Introduce the idea of light changing direction when it passes from one transparent medium to another, and the term 'refraction', and distinguish this from reflection. Help pupils to interpret what they see by explaining that they imagine light as having travelled in a straight line rather than as having been refracted (bent).
- Provide a range of glass or perspex blocks of different shapes, including rectangular and semicircular, and ask pupils to investigate their effects on a single ray of light produced by a ray box. Ask them to look for patterns in their observations of reflection when changing the angle of incidence. Establish generalisations from patterns of observations.
- Set up the 'disappearing coin in a cup of water' demonstration. Ask pupils to explain how it works.
|
|
- make generalisations from their observations of refraction,
eg that a change of direction occurs only at an interface; light bends towards the normal (inwards) when travelling from a less dense to a more dense medium, and vice versa
- draw selected angles of incidence and refraction and use these to establish generalisations, eg when the ray travels from air to glass, the angle of refraction is smaller than the angle of incidence
- draw a ray diagram to explain a phenomenon of refraction
|
