Ray diagrams
Specular reflection
Reflection from a smooth, flat surface is called Reflection in which light travelling towards a surface in one direction is all reflected in a single direction.. This is the type of reflection that happens with a flat mirror. The image in a mirror is:
- upright
- virtual
- the same distance behind the mirror as the object is in front
In a An image from which rays of light appear to come but do not do so in reality., the rays appear to diverge from behind the mirror, so the image appears to come from behind the mirror.
Diffuse reflection
If a surface is rough, When light is reflected off a surface and is scattered in different directions. happens. Instead of forming an image, the reflected light is scattered in all directions. This may cause a distorted image of the object, as occurs with rippling water, or no image at all. Each individual reflection still obeys the law of reflection, but the different parts of the rough surface reflect at different angles.
Refraction
Process by which a wave changes speed and sometimes direction upon entering a denser or less dense medium, eg a light ray changes direction when refracted by a lens. is the change in direction of a wave at a boundary.
It is important to be able to draw Diagram that represents the direction and angle of travel of light. to show the refraction of light at a boundary.
Dispersion
When light is refracted as it enters a prism, each colour is refracted by a different amount. Because each colour has a different wavelength, the speed of each colour is different. This means that the light leaving a prism is separated into its spectrum colours. This a process called dispersion.