A primary light color—red, blue, or green; these three colors produce white light when
angle of incidence
The angle between a wave striking a barrier and the line perpendicular to the surface.
angle of reflection
The angle between a reflected wave and the normal to the barrier from which it is reflected.
An angstrom is 1/100,000,000 of a centimeter.
A lens that is thinner in the middle than at the edges; used to correct nearsightedness.
A lens that is thicker in the middle than at the edges; used to correct farsightedness.
A piece of transparent or reflecting material, which contains many thousands of parallel
lines per centimeter; used to produce a light spectrum by diffraction.
A wave that does not have to travel through matter in order to transfer energy.
Transverse radiant energy waves, ranging from low frequency to very high frequency,
which can travel at the speed of light.
A substance that cannot be broken down into simpler substances by ordinary means.
A triangle with three equal angles of 60 degrees and sides of equal length.
A screen that allows only certain colors to pass through it; a transparent material that
separates colors of light.
The distance between the principal focus of a lens or mirror and its optical center.
The point that all light rays from a mirror or lens pass through.
The number of waves that pass a point in a given unit of time.
High-energy wave of high frequency and with a wavelength shorter than an x ray; released
in a nuclear reaction.
The reproduction of an object formed with lenses or mirrors.
When two or more light rays overlap exactly at the crest and the trough, they are said to be
index of refraction
The amount that light is refracted when it enters a substance; given as the ratio of speed
of light in a vacuum to its speed in a given substance.
Invisible radiation with a longer wavelength than red light and next to red light in the
electromagnetic spectrum; used in heat lamps, to detect heat loss from buildings, and to
detect certain tumors.
The addition by crossing wave patterns of a loss of energy in certain areas and reinforcement
of energy in other areas.
A toy in which reflections from mirrors make patterns. It was invented in 1819
by David Brewster.
laser (light amplification by stimulated emission of radiation)
A device that produces a highly concentrated, powerful beam of light which is all one
frequency or color and travels only in one direction.
law of reflection
Angle of incidence equals the angle of reflection.
A curved, transparent object; usually made of glass or clear plastic and used to direct light.
Light is a form of energy, traveling through the universe in waves. The wavelengths of visible
light range from less than 4,000 angstroms to more than 7,000 angstroms.
A line perpendicular to a surface.
Not transparent; no light passes through the material.
The line straight out from the center of a parabolic mirror; straight line through the center of
A thin strand of glass that transmits light down its length.
A tube with magnifying lenses or mirrors that collect, transmit, and focus light.
out of phase
When the crest of one wave overlaps the trough of another they are said to be “out of phase.”
A curved line representing the path of a projectile; the shape of the surface of a
A curved mirror.
A material that absorbs certain colors of light and reflects other colors.
A mirror with a flat surface.
Light in which all waves are vibrating in a single plane.
A transparent material with two or more straight faces at an angle to each other.
An image that can be projected onto a screen; formed by a parabolic mirror or convex lens.
The light or image you see when light bounces off a surface; bouncing a wave or ray off a surface.
A telescope in which magnification is produced by a parabolic mirror.
Bending of a wave or light ray caused by a change in speed as it passes at an angle from one
substance into another.
The spreading out of light by intersecting objects, whose size is near the wavelength.
Surface of a lens or mirror that is part of a sphere.
One of the three pure pigment colors—magenta, yellow, cyan; these pigment colors produce
black when mixed.
Semitransparent; a material that admits some light.
See-through; light can go through.
A true image is the way other people see us. It is the opposite of the image that is seen in a
Radiation that has a shorter wavelength than visible light; next to violet light in the
An image formed by a mirror or lens that cannot be projected onto a surface.
visible light spectrum
Band of visible colors produced by a prism when white light is passed through it.
The total linear length of one wave crest and trough.
Invisible electromagnetic radiation of great penetrating power.