Lower Sec Science - Light
Laws of reflection
- The angle of incidence is equal to the angle of reflection. (i=r)
- The incident ray, reflected ray and the normal at the point of incidence all lie on the same plane.
Angle of incidence, i: Angle between the incident ray and the normal
Angle of reflection, r: Angle between the reflected ray and the normal
Normal: An imaginary line that is perpendicular to the surface
Refraction
- Bending of light when it moves from one medium to another
- e.g. from glass to air, from air to diamond
The reason for bending of light when travelling from one medium to another
- Change in speed due to the difference in optical density of the medium
Optical density = a measure of the extent to which a substance is able to transmit light The more optically dense that a material is, the slower that a wave will move through the material.
In general, air/vacuum is the optically least dense medium.
Note: optical density ≠ physical density
Practice Questions:
(Please note that this is not a full coverage of the light topic, the package covers all topics in full)