Pinhole Camera Reflection of Light from Plane Surfaces

Pinhole Camera

Reflection of Light from Plane Surfaces

Both angles are measured from a line perpendicular to the surface – the “normal” line N

Smooth Surface Reflection The angle of incidence i is equal to the angle of reflection r.

Smooth surface reflection • “Smooth” as it refers to mirrors means that variations in the surface are significantly smaller than the wavelength of light. • Visible light has wavelengths from 400 to 700 nm

Rough Surface Reflection • If the surface is not smooth enough the light will reflect, but rays landing at different points will reflect at different angles.

Terminology: • Smooth surface reflection is called “specular” reflection. • Rough surface reflection is called “diffuse” reflection. • Examples: – A mirror exhibits specular reflection – A sheet of white paper exhibits diffuse reflection.

Image Formation • We can locate images by “ray tracing” – drawing the light rays on paper and reflecting them using a protractor and a ruler. image eye Virtural image

Ray Tracing, continued • Notice in the diagram that all five rays are reflected according to the rule. • The reflected rays are extended, using dotted lines, to the point where they cross behind the mirror.

image eye Virtural image

Ray Tracing – finding an image in a plane mirror • Draw a perpendicular from image through plane of mirror • Draw rays from object to midpoint to eye. (remember: øi = øf ) • Extend reflected ray as dotted line behind the mirror, to the first perpendicular • This is the location of the object

Extended Object Ray Tracing • Multiple rays can be used to image larger objects