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reflection and refraction, Picture9, Picture10, angle of incidence, angle…
reflection and refraction
The law of reflection states that:
angle of incidence = angle of reflection
The angles of incidence and reflection are measured between the light ray and the normal - an imaginary line at 90° to the surface
reflection on a smooth surface has each wave direction being parallel to the next. the reflection forms a clear image, which will appear as if it is behind the surface, leg through a mirror or glass
if the surface is rough, an image will be distorted, such as with water, or no image is formed at all. each individual ray will still obey the law of reflection, but the normal for each ray is different
:
refraction
Different materials have different densities. Light waves may change direction at the boundary between two transparent materials. Refraction is the change in direction of a wave at such a boundary.
The density of a material affects the speed that a wave will be transmitted through it. In general, the denser the transparent material, the more slowly light travels through it.
Glass is denser than air, so a light ray passing from air into glass slows down. If the ray meets the boundary at an angle to the normal, it bends towards the normal.
The reverse is also true. A light ray speeds up as it passes from glass into air, and bends away from the normal by the same angle.
ray diagram
Refraction can cause optical illusions as the light waves appear to come from a different position to their actual source.
angle of incidence
angle of reflection
angle of refraction
glass
air
normal
