Key Terms

aberration
a distortion in an image produced by a lens
angle of incidence
the angle, with respect to the normal, at which a ray meets a boundary between media or a reflective surface
angle of reflection
the angle, with respect to the normal, at which a ray leaves a reflective surface
angle of refraction
the angle between the normal and the refracted ray
central axis
a line perpendicular to the center of a lens or mirror extending in both directions
chromatic aberration
an aberration related to color
concave lens
a lens that causes light rays to diverge from the central axis
concave mirror
a mirror with a reflective side that is curved inward
converging lens
a convex lens
convex lens
a lens that causes light rays to converge toward the central axis
convex mirror
a mirror with a reflective side that is curved outward
critical angle
an incident angle that produces an angle of refraction of 90°
dispersion
separation of white light into its component wavelengths
diverging lens
a concave lens
focal length
the distance from the focal point to the mirror
focal point
the point at which rays converge or appear to converge
incident ray
the incoming ray toward a medium boundary or a reflective surface
index of refraction
the speed of light in a vacuum divided by the speed of light in a given material
law of reflection
the law that indicates the angle of reflection equals the angle of incidence
law of refraction
the law that describes the relationship between refractive indices of materials on both sides of a boundary and the change in the path of light crossing the boundary, as given by the equation n1 sinθ1θ1 = n2 sinθ2θ2
ray
light traveling in a straight line
real image
an optical image formed when light rays converge and pass through the image, producing an image that can be projected onto a screen
refracted ray
the light ray after it has been refracted
Snell’s law
the law of refraction expressed mathematically as n1sinθ1=n2sinθ2n1sinθ1=n2sinθ2
total internal reflection
reflection of light traveling through a medium with a large refractive index at a boundary of a medium with a low refractive index under conditions such that refraction cannot occur
virtual image
the point from which light rays appear to diverge without actually doing so