Law of Reflection and Plane Mirrors The angle

Law of Reflection and Plane Mirrors

The angle of reflection is equal to the angle of incidence incident ray normal 40 o reflected ray 40 o reflecting surface point of incidence The First Law of Reflection: The angle of incidence equals the angle of reflection. Angles are measured from the normal, NOT from the reflecting surface.

The Law of Reflection incident ray normal i reflected ray r point of incidence reflecting surface The angle of reflection (r) is equal to the angle of incidence (i). The reflected ray and the incident ray are on opposite sides of the normal. The incident ray, reflected ray, and normal are all on the same plane.

Law of Reflection - Key Terms ¡ Incident ray – the light ray travelling toward the mirror (or reflecting surface) ¡ Reflected ray – the light ray that has ‘bounced’ off a reflecting surface ¡ Normal – line perpendicular to a surface such as a mirror ¡ Angle of incidence (i) – the angle between the incident ray and the normal ¡ Angle of reflection (r) – the angle between the reflected ray and the normal

Types of Reflection ¡ ¡ ¡ When more than one incident light ray reflect off a surface, the laws of reflection still hold but the surface effects the way you see the reflected rays. Specular reflection l reflection of light off a smooth, shiny surface. l Example: plane mirror, disco ball Diffuse reflection l reflection of light off an irregular or dull surface. l Example: rough aluminum foil, rough lake

Drawing Normals Use a protractor and ruler to draw normals to the lines at each of the points shown.

Same Plane

Disco Ball – Specular Reflection

Reflecting Lake – Diffuse Reflection