A - Abbreviation for "ampere" a unit of electrical current.
absorption - Loss or dissipation of energy as it travels through a medium, Example: radio waves lose some of their energy as they travel through the atmosphere.
AC - Abbreviation for "Alternating Current"
acceptor atoms - Trivalent atoms that accept free electrons from pentavalent atoms.
AC coupling - Circuit that passes an AC signal while blocking a DC voltage.
AC/DC - Equipment that will operate on either an AC or DC power source.
AC generator - Device used to transform mechanical energy into AC electrical power.
AC load line - A graph representing all possible combinations of AC output voltage and current for an amplifier.
AC power supply - Power supply that delivers an AC voltage.
active component - A component that changes the amplitude of a signal between input and output.
active filter - A filter that uses an amplifier in addition to reactive components to pass or reject selected frequencies.
active region - The region of BJT operation between saturation and cutoff used for linear amplification.
AC voltage - A voltage in which the polarity alternates.
ADC - Abbreviation for "analog to digital converter"
Admittance - (symbol "Y") Measure of how easily AC will flow through a circuit. Admittance is the reciprocal of impedance and is measured in siemens.
AF - Abbreviation for "audio frequency".
AFC - Abbreviation for "automatic frequency control".
AGC - Abbreviation for "automatic gain control"
alkaline cell - A primary cell that delivers more current than a carbon-zinc cell. Also known as an "alkaline manganese cell".
alligator clip - Spring clip on the end of a test lead used to make a temporary connection.
alpha - Ratio of collector current to emitter current in a bipolar junction transistor (BJT). Greek letter alpha "a" is the symbol used.
alternating current - An electric current that rises to a maximum in one direction, falls back to zero and then rises to a maximum in the opposite direction and then repeats.
alternator - Name for an AC generator.
AM - Abbreviation for "amplitude modulation"
ammeter - A meter used to measure current.
ampere - Unit of electrical current.
amplifier - A circuit that increases the voltage, current, or power of a signal.
amplitude - Magnitude or size of a signal voltage or current.
analog - Information represented as continuously varying voltage or current rather than in discrete levels as opposed to digital data varying between two discrete levels.
anode - The positive electrode or terminal of a device. The "P" material of a diode.
antenna, transmitting - A device that converts an electrical wave into an electromagnetic wave that radiates away from the antenna.
antenna, receiving - A device that converts a radiated electromagnetic wave into an electrical wave.
apparent power - Power attained in an AC circuit as a product of effective voltage and current which reach their peak at different times.
arc - Discharge of electricity through a gas such as lightning discharging through the atmosphere.
armature - The rotating or moving component of a magnetic circuit.
armstrong oscillator - An oscillator that uses an isolation transformer to achieve positive feedback from output to input.
astable multivibrator - An oscillator that produces a square wave output from a DC voltage.
atom - The smallest particle that an element can be broken down into and still maintain its unique identity.
atomic number - The number of positive charges or protons in the nucleus of an atom.
attenuate - To reduce the amplitude of an action or signal. The opposite of amplification.
audio - Relating to frequencies that can be heard by the human ear. Approximately 20 Hz. to 20 kHz.
autotransformer - A single winding transformer where the output is taken from taps on the winding.
average value - A value of voltage or current where the area of the wave above the value equals the area of the wave below the value.
AVC - Abbreviation for "automatic volume control"
avionics - Aviation electronics.
AWG - Abbreviation for "American wire gauge". A gauge that assigns a number value to the diameter of a wire.