An opening.
The bending of waves around obstacles, or the spreading of waves by passing them through an aperture.
A process by which the concentration or density of something isdecreased.
The complete range of electromagnetic waves on a continuous distribution from a very low range of frequencies and energylevels, with a correspondingly long wavelength, to a very high range of frequencies and energy levels, with a correspondingly short wavelength. Included on the electromagnetic spectrum are long-wave and short-wave radio; microwaves; infrared, visible, and ultraviolet light; x rays, and gamma rays.
A transverse wave with electric and magnetic fields that emanate from it. The directions of these fields are perpendicular to one another, and both are perpendicular to the line of propagation for the wave itself.
The number of waves passing through a given point during the interval of one second. The higher the frequency, the shorter the wavelength.
A unit for measuring frequency, named after nineteenth—century German physicist Heinrich Rudolf Hertz (1857-1894).
Contact between a ray—for example, a light ray—and a surface. Types of incidence include reflection and refraction.
A substance through which light travels, such as air, water, or glass. Because light moves by radiation, it does not require a medium, and, in fact, movement through a medium slows the speed of light somewhat.
An area of physics that studies the production and propagation of light.
The phenomenon whereby certain metalsacquire an electrical potential when exposed to light.
A particle of electromagnetic radiation—for example, light—carryinga specific amount of energy, measured in electron volts (eV).
A three-dimensional glassshape used for the diffusion of light rays.
The act or state of traveling from one place to another.
The transfer of energy by means of electromagnetic waves, which require no physical medium (for example, water or air) for the transfer. Earth receives the Sun's energy (including its light), via the electromagnetic spectrum, by means of radiation.
In geometry, a ray is that part of a straight line that extends in one directiononly. The term "ray" is used to describe the directed line made by light as it moves through space.
A type of incidence whereby a light ray is returned toward its source rather than being absorbed at the interface.
The bending of a lightray that occurs when it passes through a dense medium, such as water or glass.
The continuous distribution of properties in an ordered arrangement across an unbroken range. Examples of spectra (the plural of "spectrum") include the colors of visible light, or the electromagnetic spectrum of which visiblelight is a part.
A wave in which the vibration or motion is perpendicular to the direction in which the wave is moving.
An area of space devoid of matter, including air.
The distance between a crest and the adjacent crest, or the trough and an adjacent trough, of a wave. The shorter the wavelength, the higher the frequency.
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