lag - Difference in time between two waveforms of the same frequency expressed in degrees. Example: One waveform lags another waveform by a certain number of degrees.
laminated core - Core made up of sheets of magnetic material insulated from one another by an oxide or varnish.
lamp - Device that produces light.
laser - Device that produces a very narrow intense beam of light. The name is an axcronym for "light amplification by stimulated emission of radiation.
lead - The angle by which one alternating signal leads another in time. Opposite of lag. Also a wire that connects two points in a circuit.
lead-acid cell - Cell made up of lead plates immersed in a sulphuric acid electrolyte. An automobile battery usually consists of six lead-acid cells.
leakage - Small undesirable flow of current through an insulator or dielectric.
LED - Abbreviation for "light emitting diode."
left-hand-rule - If fingers of the left hand are placed around a wire so that the thumb points in the direction of electron flow, the fingers will be pointing in the direction of the magnetic field being produced by the conductor.
Lenz's law - The current induced in a circuit due to a change in the magnetic field is so directed as to oppose the flux, or to exert a mechanical force to oppose the motion.
level detector - An op-amp circuit that compares two inputs and provides a DC output indicating the polarity relationship between the inputs. A
lie detector - Piece of electronic equipment also called a polygraph used to determine whether a person is telling the truth by looking for dramatic changes in blood pressure, body temperature, breathing rate, heart rate and skin moisture in response to questions.
light - Electromagnetic radiation in a band of frequencies that can be received by the human eye.
lifetime - The time from the creation of an electron hole pair until recombination occurs.
light-emitting diode - A semiconductor diode that converts electric energy into electromagnetic radiation at a visible and near infrared frequencies when its pn junction is forward biased.
limiter - Circuit or device that prevents some portion of its input from reaching the output. A clipper.
linear - Relationship between input and output in which the output varies in direct proportion to the input.
linear scale - A scale in which the divisions are uniformly spaced.
line regulation - The ability of a voltage regulator to maintain a constant voltage when the regulator input voltage varies.
live - Term used to describe a circuit or piece of equipment that is on and has current flow within it.
load - A source drives a load. Whatever component or piece of equipment is connected to a source and draws current from a source is a load on that source.
load current - Current drawn from a source by a load.
load impedance - Vector sum of reactance and resistance in a load.
loading effect - Large load impedance will draw a small load current and so loading of the source is small. (light load). A small load impedance will draw a large load current from the source. (heavy load).
load regulation - The ability of a voltage regulator to maintain a constant output voltage under varying load currents.
load resistance - Resistance of a load.
logic - Science of dealing with the principle and applications of gates, relays and switches.
loss - Term used to describe a decrease in power.
low pass filter - A tuned circuit designed to pass all frequencies below a designated cut-off frequency.