2- REFLECTION AND

FLAT MIRRORSDistinguish between specular and diffuse reflection of

light.

Apply the law of reflection for flat mirrors.

Describe the nature of images formed by flat mirrors

Reflection Light travels in a straight line path through a

substances until it encounters a different substance, at which point its path will change

All substances absorb at least some incoming light and reflects the restNo surface is a perfect reflector

Reflection is the change in direction of an electromagnetic wave at a surface that causes it to move away from the surface.

Reflection The texture of a surface

affects how it reflects light. Diffuse reflection is

reflection from a rough, texture surface such as paper or unpolished wood.

Specular reflection is reflection from a smooth, shiny surface such as a mirror or a water surface.

The angle of incidence () is the the angle between a ray that strikes a surface and the line perpendicular to that surface at the point of contact.

The angle of reflection (’) is the angle formed by the line perpendicular to a surface and the direction in which a reflected ray moves.

The angle of incidence and the angle of reflection are always equal.

The law of reflection states that the angle between the incoming ray and the surface equals 90°-θ and the angle between the reflected ray and the surface equals 90°-θ’

Flat Mirrors

The “object” is a source of spreading, or diverging, light rays. Every point on an object is a source of

diverging light rays. The image formed by rays that appear

to come from the image point behind the mirror—but never really do—is called a virtual image.A virtual image can never be displayed on a

physical surface.

Flat Mirrors The object distance from the mirror, p, is

equal to the image distance, q (di=do) The virtual image is the same size, h’,

as the object, h

A. Draw arrangement of object with respect to the mirror

B. Draw two rays

1. From top of object perpendicular to the mirror’s surface, this ray reflects back on its self, (0° angle with normal)

2. From top of object to the mirror at an angle not perpendicular (θ)

3. Draw reflected ray from normal at an angle equal to the angle of incidence (θ’)

C. Trace (with dotted lines) both reflected rays back to the point from which they appear to have originated (behind the mirror)

D. The point at which these dotted rays meet is the image point