reflection

• when waves arrive at a boundary between two different materials, they can be absorbed, transmitted or reflected
• boundary - interference between two materials (the medium)
• the waves can be absorbed by the material the wave is trying to cross into - this transfers energy to the materials energy stores
• if waves are transmitted - they carry on travelling through the new material, often leading to refraction
• if the wave is reflected, transmitted or absorbed depends on the wavelength and the properties of the materials involved
• angle of incidence = angle of reflection
• the angle of incidence is the angle between the incoming wave and the normal
• the angle of reflection is the angle between the reflected wave and the normal
• the normal is an imaginary line that's perpendicular to the surface at the point of incidence (where the wave hits the boundary) usually shown as a dotted line
• simple ray diagram for reflection

  
• reflection can be specular or diffuse
• When one medium ends, another medium begins; the interface of the two media is referred to as the boundary and the behavior of a wave at that boundary is described as its boundary behavior.
• specular reflection happens when a wave is reflected in a single direction by a smooth surface , e.g. when a light is reflected by a mirror

  
• diffuse reflection is when a wave is reflected by a rough surface and the reflected rays are scattered in lots of different directions. this happens as the normal is different for each incoming ray, which means the angle of incidence is different for each ray. Do not get clear reflection

  
• Diffuse reflection occurs when a surface is not optically smooth
• In diffuse the ray of incidence still equals ray of reflection , but the Normal is different for every ray.
• In diffuse reflection, the incoming rays are parallel , but the reflective waves are not