- using physical representation: relating to a system or
device that represents data variation by a measurable physical quality.
- something that conveys heat or electricity: a substance,
body, or medium that allows heat, electricity, light, or sound to pass
along it or through it. Metals are good conductors of heat because of
the high concentration of free electrons they contain.
- broadcasting wavelength: a wavelength on which a radio or
television signal is broadcast and to which a receiving set can be
- gas around celestial body: the mixture of gases that
surrounds a celestial body such as the Earth.
- rate of recurrence: the number of times that something such
as an oscillation, a waveform, or a cycle is repeated within a
particular length of time, usually one second. Symbol Symbol f
- electrically charged atom or atom group: an atom or group
of atoms that has acquired an electric charge by losing or gaining one
or more electrons.
- device for sending and receiving radio waves: a metallic
piece of equipment of variable shape, used in the sending and receiving
of television or radio signals.
- have or cause failure in a circuit: to have or cause a
failure in an electrical circuit by creating a connection of low
resistance across which an excessive current flows.
- unit of electrical power: the international ( SI ) unit of
power equal to the power produced by a current of one ampere acting
across a potential difference of one volt. Symbol W.
- unit of electrical resistance: the SI unit of electrical
resistance, equal to the resistance between two points on a conductor
when a potential difference of 1 volt produces a current of 1 ampere.
- unit of electric potential difference: the unit of
electromotive force and electric potential difference equal to the
difference between two points in a circuit carrying one ampere of
current and dissipating one watt of power. Symbol V
- measure of rate of doing work: a measure of the rate of
doing work or transferring energy, usually expressed in terms of wattage
or horsepower. Symbol P
- representing sound/light waves as numbers: representing a
varying physical quantity, such as sound or light waves, by means of
discrete signals interpreted as numbers, usually in the binary system,
as in a digital recording or digital television.
- unidirectional electrical current: electrical current that
flows in only one direction and has a fairly constant average value.
- ionized layers in upper atmosphere: four layers of the
Earth's upper atmosphere in which incoming ionizing radiation from space
creates ions and free electrons that can reflect radio signals, enabling
their transmission around the world.
- change in frequency because of motion: a perceived change in
the frequency of a wave as the distance between the source and the
observer changes. For example, the sound of a siren on a moving vehicle
appears to change as it approaches and passes an observer.
- property of electric circuit: the property of an electric
circuit or device whereby an electromotive force is created by a change
of current in it or in a circuit near it. Symbol L
- The Federal Communications Commission (FCC) is an
independent United States government agency, directly responsible to
Congress. The FCC was established by the Communications Act of 1934 and
is charged with regulating interstate and international communications
by radio, television, wire, satellite and cable. The FCC's jurisdiction
covers the 50 states, the District of Columbia, and U.S. possessions.
- lowest layer of the atmosphere: the lowest and most dense
layer of the atmosphere, extending 8 to 16 km (5 to 10 mi), in which
temperature decreases with rising altitude and most weather occurs.
- 1. ability to store electric charge: the ability of a
substance to store electric charge 2. measure of electric charge
storage: a measure of the capacitance of a substance, equal to the
surface charge divided by the electric potential. Symbol C 3. part of
electric circuit: the part of an electric circuit that has capacitance
- reversing current: an electric current that regularly
- 1. ampere: an ampere 2. amplifier: an amplifier (informal)
- power supply or source: a supply or source of electrical,
mechanical, or other form of power.
- energy emitted in rays or waves: any kind of energy that is
emitted from a source in the form of rays or waves, for example, heat,
light, or sound.
- line from eye to object: an imaginary line from an observer
to a distant object.
- smallest part of element: the smallest portion into which
an element can be divided and still retain its properties, made up of a
dense, positively charged nucleus surrounded by a system of electrons.
Atoms usually do not divide in chemical reactions except for some
removal, transfer, or the exchange of specific electrons.
- signal's maximum value: the maximum value of an alternating
- electron not bonded to an atom: an electron that is not
bonded to an atom or molecule and so is free to move under external
electric or magnetic fields.