Le Chatelier′s Principle
Predicts that when a stress is applied to an equilibrium mixture, the equilibrium will shift to relieve the stress.
the process by which soluble materials in the soil, such as salts and nutrients, are washed into a lower layer of soil or are dissolved and carried away by water.
A soft, malleable and ductile metallic element that has been known of and used since prehistoric times.
Lead Acid Battery
A battery with electrodes of lead oxide and metallic lead that are separated by an electrolyte of sulphuric acid.
Lead Hole
A starting hole for large drills to serve as a guide.
Lead II Acetate


Used as a reagent to make other lead compounds and as a fixative for some dyes.

Lead II Carbonate


Decomposes readily into Lead II Oxide and carbon dioxide at 200°C and can be reduced to lead using carbon monoxide.

Lead II Chromate IV


Used as a pigment due to the strong yellow colour.

Lead II Oxide


Lead monoxide varies in colour from pale yellow to brown, used in the manufacture of glass, paints, varnishes and glazes.

Lead II Sulphide


Grey crystalline solid.

Lead Inductance
Inductance of the lead wires connecting the components.
Lead IV Oxide


Lead dioxide a dark brown powder, strong oxidizing agent.

Lead Screw
A device for translating rotary motion into linear motion.
Lead Sheath
A continuous jacket of lead moulded around a single conductor or multiple conductor cable.
Lead Term
A control system component that anticipates future inputs based on the current signal trend.
Lead Tetraethyl
Alternative name for Tetraethyl Lead.
The lead of a helical gear tooth is the axial advance resulting from one full revolution of the helix on the cylinder.
The opposite of Lag.
A wire or connection.
Leaded Glass Window
Windows that are constructed of various shaped pieces of glass plate that are held together by lead solder between panes.
Leading Edge
The edge of an airfoil which first meets the airstream in normal flight.
Leading Strand
The DNA strand that, during replication, is synthesized in the same direction in which the replication fork moves.
Leaf Springs
Either a simple beam used as a spring or laminations of steel.
An old imperial unit of distance.
Leak Rate
The rate of gas leakage into or out of a system.
In a Fourier Transform the signal is assumed to be periodic. If a pure sine wave does not repeat exactly within the time window, it is truncated. this truncation will lead to the frequency domain resultant being smeared (leakage) and not a single frequency.
Leakage Current
The small amount of current that flows through the dielectric between the conductors of a transmission line.
Leakage Flux
Magnetic flux lines produced by the primary winding that do not link the turns of the secondary winding.
Leakage Resistance
The electrical resistance that opposes the flow of current through the dielectric of a capacitor.
Lean Burn
A fuel air mixture that contains higher amounts of air than normally used.
Lean Mixture
A mixture in which the proportion of air to fuel is greater than that theoretically necessary for completes combustion.
Leap Day
The extra day added to a year to make it have 366 days. Leap days are added on in February creating the 29th day of the month that only exists during leap years.
Leap Year
Leap years are years with 366 days, instead of the usual 365.
Leapfrog Test
A check routine which eventually occupies every possible position in the memory.
Least Common Multiple
The least common multiple of a set of integers is the smallest integer that is an exact multiple of every number in the set.
Least Significant Bit (LSB)
The bit within a digital word that represents the smallest possible coded value.
Least Squares
Any statistical procedure that involves minimizing the sum of squared differences.
Least Upper Bound
The least upper bound of a set of numbers is the smallest number that is larger than every member of the set.
Least-Squares Solution of a Linear System
A least-squares solution to a system of linear equations Ax = b is a vector x that minimizes the length of the vector Ax - b.
Leclanché Cell
A electrolytic cell also known as a dry cell that uses a moist paste rather than a liquid as an electrolyte.
A diode that emits light when current is passed through it.
Abbreviation of Live End Dead End.
Leeuwenhoek, Antonie van
Commonly known as "the Father of Microbiology", and considered to be the first microbiologist.
Left Atrium
The left upper chamber of the heart.
Left Hand Rule
The procedure for finding electron-flow direction in a wire by grasping it so the fingers point in the direction of the magnetic lines of force.
Left Hand Thread
A screw thread that is screwed in by rotating counterclockwise.
Left Hand Tractor Propeller
The propeller rotated anti-clockwise when viewed from the rear.
Left Ventricle
The left lower chamber of the heart
The plural of Lemma.
A proposition that is useful mainly for the proof of some other theorem.
Lempel-Ziv Welch Compression
Algorithm used by the Unix compress command to reduce the size of files, eg. for archival or transmission.
The SI unit of length is the metre.
Length Contraction
An observer in motion relative to an object measures the length of that object along the direction of motion to be contracted when compared to the length measured by an observer at rest relative to the object.
Lennard-Jones Potential
Most often used in modelling van der Waals interactions.
Lenoir, Jean-Joseph-Etienne
French inventor and internal combustion engine pioneer who patented a single cylinder engine running on kerosene in 1860.
A lens is an optical component whos surface curvature and refractive index are designed such that the direction of light incident upon it is controlled.
Lens Mount
A mechanical and often also electrical interface between a photographic camera body and a lens.
Lens Thread M39
Also known as the Leica L-Mount. This is 39mm x 26tpi.
Lens Thread M42
This is an metric 42x1.0mm thread used for single reflex cameras before the bayonet couplings became commonplace.
Lens Thread T2
42mm x 0.75mm lens adaptor thread used by Tamron.
Lenticular Cloud
A cloud species which has elements resembling smooth lenses or almonds and more or less isolated.
Lenticular Galaxy
An intermediate form of galaxy, between elliptical galaxies and spiral galaxies.
Lenzs Law
A basic law which states that an induced current set up by the relative motion of a conductor and a magnetic field always flows in such a direction as to form a magnetic field which opposes the motion.
Leonardo of Pisa
Fibonacci was also known as Leonardo of Pisa.
Alternative name for Iron Hydroxide.
There are a number of different noise criteria measurements used by local authorities to determine noise levels in the community.
A distribution that is more peaked than a normal distribution.
A family of elementary particles that includes the electron, muon, tau, and their associated neutrinos.
Less Than
An inequality that says the variable on the left is less than the variable to the right of the inequality.
Less than or Equal to
An inequality that says the variable on the left is less than or equal to the variable to the right of the inequality.
Letter Drills
This system of numbering drills is no longer used, but may be of use in deciphering old drawings.


A naturally occuring aliphatic amino acid with a nonpolar side chain.

Abbreviation of Low Emission Vehicle.
The condition where an item is perpendicular to the force of gravity. The level of a signal is its amplitude.
Level Cross Counting
One count is recorded each time the positive sloped portion of the load exceeds a present level above the reference load, and each time the negative sloped portion of the load exceeds a present level below the reference load.
One of the basic tools that date from prehistoric times.
Lever Arm Steering System
This steering system allows large steering angles to be achieved at the wheels.
Lever Rule
Mathematical expression whereby the relative phase amounts in a two-phase alloy at equilibrium may be computed.
Lever-Type Shock Absorber
A damper operated by a lever arm from a chassis-mounted hydraulic damper unit.
A chiral molecule which rotates plane-polarized light to the left.
Lewis Structure
A model pioneered by Gilbert N. Lewis and Irving Langmuir that represents the electronic structure of a molecule by writing the valence electrons of atoms as dots.
Leyden Jar
An early form of capacitor.