The effect produced by the existence of an electric charge, such as an electron, ion, or proton, in the volume of space or medium that surrounds it. Note: Each of a distribution of charges contributes to the whole field at a point on the basis of superposition. A charge placed in the volume of space or in the surrounding medium has a force exerted on it.

Of a transmission medium, its length expressed as a multiple or submultiple of the wavelength of a periodic electromagnetic or electrical signal propagating within the medium. Note 1: The wavelength may be expressed in radians or in artificial units of angular measure, such as degrees. Note 2: In both coaxial cables and optical fibers, the velocity of propagation is approximately two-thirds that of free space. Consequently, the wavelength will be approximately two-thirds that in free space, and the electrical length, approximately 1.5 times the physical length. 2. Of a transmission medium, its physical length multiplied by the ratio of (a) the propagation time of an electrical or electromagnetic signal through the medium to (b) the propagation time of an electromagnetic wave in free space over a distance equal to the physical length of the medium in question. Note: The electrical length of a physical medium will always be greater than its physical length. For example, in coaxial cables, distributed resistances, capacitances and inductances impede the propagation of the signal. In an optical fiber, interaction of the lightwave with the materials of which the fiber is made, and fiber geometry, affect the velocity of propagation of the signal. 3. Of an antenna, the effective length of an element, usually expressed in wavelengths. Note 1: The electrical length is in general different from the physical length. Note 2: By the addition of an appropriate reactive element (capacitive or inductive), the electrical length may be made significantly shorter or longer than the physical length.

A telephone in which the operating power is obtained either from a battery located at the telephone, i.e., a local battery, or from a telephone central office, i.e., a common battery.

Deprecated term. See optoelectronic.

Any one of a number of phenomena that occur when an electromagnetic wave in the optical spectrum interacts with an electric field, or with matter under the influence of an electric field. Note 1: Two of the most important electro-optic effects having application as modulation mechanisms in optical communication are the Kerr effect and the Pockels effect, in which birefringence is induced or modified in a liquid (Kerr effect) or solid (Pockels effect). Note 2: The term “electro-optic” is often erroneously used as a synonym for “optoelectronic.”

An optical device in which a signal-controlled element is used to modulate a beam of light. Note 1: The modulation may be imposed on the phase, frequency, amplitude, or direction of the modulated beam. Note 2: Modulation bandwidths into the gigahertz range are possible using laser-controlled modulators.

Intelligence information other than signals intelligence derived from the optical monitoring of the electromagnetic spectrum from ultraviolet (0.01 m) through the far infrared (1000 m). [JP1]

The technology associated with those components, devices and systems which are designed to interact between the electromagnetic (optical) and the electric (electronic) state. [JP1] Note 1: The operation of electro-optic devices depends on modification of the refractive index of a material by electric fields. Note 2: In a Kerr cell, the refractive index change is proportional to the square of the electric field, and the material is usually a liquid. Note 3: In a Pockels cell, the refractive index change varies linearly with the electric field, and the material is a crystal. Note 4: “Electro-optic” is often erroneously used as a synonym for “optoelectronic”.

Acronym for electro-optical intelligence.

Facsimile recording by means of a chemical reaction brought about by the passage of a signal-controlled current through the sensitized portion of the record sheet.