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REFLECTION AND REFRACTION
Reflection occurs when an object or a wave bounces back off a surface.
The Law of Reflection: The angle of incidence equals the angle of reflection.
Three types of Mirrors:
1. Plane mirror – A flat sheet of glass that has a smooth silver coating on one side.
 The smooth coating causes a clear image to form and be reflected.
 The image is virtual image because it is an upright image formed where the light
seems to come from. Images formed from plane mirrors are reversed with respect
to left and right.
 Plane mirrors make the image appear to be located behind the mirror.
2. Concave mirror – A mirror with a surface that curves inward in the center.
 Parallel light rays are reflected at an angle so they meet at the focal point in front of
the mirror on the optical axis.
 The optical axis is an imaginary line that divides the mirror in half.
 The focal point is where the reflected light rays meet.
 The length of the focal point depends on the curve of the mirror.
More curve = closer focal point
Less curve = farther focal point
 Concave mirrors can form either real or virtual images depending on the distance
between the object being reflected and the mirror. A real image forms when the
rays actually meet.
a) If the object is between the focal point and the mirror then a virtual image
is formed.
b) If the object is beyond the focal point then a real image is formed. A
virtual image formed by a concave mirror is always enlarged.
 Images formed from concave mirrors always appear enlarged.
 Concave mirrors are used to magnify objects.
3. Convex mirror – A mirror with a surface that curves outward at the center.
 The light rays spread outward when reflected from the surface of a convex mirror.
 The rays appear to come from a focal point behind the mirror but the rays never
actually meet,
 Images formed from a convex mirror are always virtual images and always appear
smaller than the object being reflected.
 Convex mirrors are used for side-view mirrors on cars and as security mirrors in
stores and banks.