Chapter 29 Reflection and Refraction

When waves interact with matter, they can be reflected, transmitted, or a combination of both. Waves that are transmitted can be refracted.

Reflection When a wave reaches a boundary between two media, usually some or all of the wave bounces back into the first medium. The part of the wave that comes back is the reflection.

Defining Normal? Normal: Perpendicular to the plane of a surface. The normal to the floor points straight up. The normal to the ceiling points straight down.

The Law of Reflection Angle of Incidence = Angle of Reflection

Refraction When a wave hits a boundary it changes its speed upon crossing the boundary between two media. (Media is plural for medium) If that wave hits the boundary at any angle other than normal to the surface, it bends. This bending is called Refraction.

A Property of Matter Index of Refraction: A measure of how much slower light moves through a material. The higher the number, the slower light moves.

Toward Normal or Away From Normal When light moves from a lower Index of Refraction to a higher index of refraction, the wave bends towards the normal. When light moves from a higher Index of Refraction to a lower index of refraction, the wave bends away from the normal.

Effects of Refraction in Daily life Think for a moment Write down what is going on in each picture.

Diffraction Bending of waves when they encounter an obstacle.