Reflection and refraction

• Reflection and refraction of light explains how people see images, colour and even optical illusions.
• Waves, including sound and light, can be reflected at the boundary between two different materials.
• The reflection of sound causes echoes.
• The law of reflection states that: angle of incidence = angle of reflection.
• The angle of incidence is the angle between the normal and the incident ray.
• The reflection close angle of reflection is the angle between the reflected ray and the normal, which is an imaginary line drawn at 90 degrees to the reflecting surface.
• All angles are measured to this line.
• A ray diagram shows how an image forms in a plane mirror.
• Diffuse reflection is when light is reflected off a surface and is scattered in different directions, 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 are at different angles.