Reflection of Light

• reflection - is the bouncing back of light into the same medium it has been traveling after striking a surface
• incident ray - the ray that strikes the surface
• reflected ray - the ray that rebounds from the surface
• normal - the line perpendicular to the surface at the point of incidence
• angle of incidence - the angle between the incident ray and the normal
• angle of reflection - the angle between the reflected ray and the normal
• regular reflection - the reflection from smooth surfaces
• diffuse reflection - reflection from a rough surface
• angle of incidence = angle of reflection
• plane mirror - a mirror with a flat surface
• spherical mirror - has a reflecting surface taken from the surface of a sphere
• concave mirror - curves inward in the direction of the incident rays
• convex mirror - bulges outward to the incident rays
• the image formed by mirrors may be real or virtual
• real image - is formed by the actual intersection of reflected rays

  • is formed in front of the mirror and is always upside down relative to the object
• virtual image - is always formed behind the mirror and is always upright relative to the object
• magnification - the size of the image relative to the size of the object
• magnification of 1 = image & object are of same size

  magnification less than 1 = image is smaller than object

  magnification greater than 1 = image is larger than object
• images formed by plane mirrors are always virtual, upright, and the same size as the object
• center of curvature (C) - the center of the sphere from where the mirror was taken
• vertex - it is the center of the mirror; sometimes called the pole of the mirror
• radius of curvature - is the radius of the sphere; it is the distance between C & V
• principal axis - a straight line joining C & V
• aperture - this refers to the width of the mirror
• principal focus - is the point where the reflected rays meet (if converging mirror) or the point where the reflected rays seem to come from behind a diverging mirror
• focal length - the distance from the vertex to the principal focus/focal point
• point of incidence - the point where the incident ray strikes