Investigate the reflection of light by different types of surface and the refraction of light by different substances.
1. Set up a pointer s so that a narrow ray of light is produced.
2. Use the pointer to shine a ray of light at the point where the normal meets the block. This is the incident ray.
3. The angle between the normal and the incident ray is called the angle of incidence. Move the ray box or paper to change the angle of incidence. The aim is to see a clear ray reflected from the surface of the block and another clear ray leaving the opposite face of the block.
4. Using a pencil on the paper, mark the path of:
◆ the incident ray with a cross
◆ the reflected ray with a cross
◆ the ray that leaves the block with two crosses – one near the block and the other further away5.
5. Remove the block. Join the crosses to show the paths of the light rays.
6. Repeat steps 2 to 7 for a rectangular glass block.
7. Measure the angle of incidence, angle of refraction and angle of reflection for each block.