Elapsed Time
A period of time that has passed, usually between a given starting time and ending time.
Elastic Collisions
When two bodies collide their total momentum is conserved unless external forces act on them.
Elastic Deformation
A non-permanent deformation that totally recovers upon release of an applied stress.
Elastic Hysteresis
Difference between strain energy required to generate a given stress in a material and elastic energy at that stress.
Elastic Limit
The maximum load that a body can experience and still return to its original shape.
Elastic Strain
Dimensional changes accompanying stress where the original dimensions are restored upon release of the stress.
A material is elastic if it returns to it's original shape after being deformed.
A polymeric material that may experience large and reversible elastic deformations.
Electric Charge
A property used to explain attractions and repulsions between certain objects.
Electric Constant
e0 = 8.854187817x10-12Fm-1
Electric Current
Flow of electric charge through a medium, this charge is typically carried by moving electrons in a conductor such as wire.
Electric Dipole
An object whose centres of positive and negative charge do not coincide.
Electric Dipole Moment
A measure of the degree of polarity of a polar molecule.
Electric Discharge
The flow of electricity through a gas, resulting in the emission of radiation that is characteristic of the gas and of the intensity of the current.
Electric Field
A field of forces that act on any electric charge placed within it. The stronger the field, the stronger the force that acts on the charge.
Electric Field Probe
A short antenna with a coaxial cable lead, used for the detection of high impedance E-field source signals over a very short range.
Electric Heating
A system that imparts heat or holds something to be heated, controlled by electric current.
Electric Motor Bearings
The bearings that support the armature and allow it to rotate relative to the stator.
Electric Motor Efficiency
The efficiency of a motor is the ratio of electrical power input to mechanical power output.
Electric Motor Failure
Most motor failures stem from damaged bearings or stator windings.
Electric Motor Load
Any device driven by a motor.
Electric Motor Noise
There are numerous applications of electric motors and the type of noise produced by each may be very specific to the installation and type of motor.
Electric Motor Reaction
The force created by generator armature current that tends to oppose the normal rotation of the armature.
Electric Motor Starter
Large resistive devices placed in series with dc motor armatures to prevent the armature from drawing excessive current until armature speed develops counter emf.
Electric Motor Windings
Wires that are laid in coils, usually wrapped around a laminated soft iron magnetic core so as to form magnetic poles when energized with current.
Electric Motors
There are a number of different types of electric motor: AC Induction Motors, Brush Direct Current Motors, Brushless Direct Current Motors and Stepper Motors.
Electric Vehicle
A vehicle with one or more electric motors for propulsion.
Electrical Conductivity
The capacity of a material to conduct electric current.
Electrical Connector
An electro-mechanical device for joining electrical circuits as an interface using a mechanical assembly.
Electrical Energy Storage
The storage of electrical energy in a device such as a capacitor.
Electrical Engineer
An engineer concerned with electrical devices and systems and with the use of electrical energy.
Electrical Engineering
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Electrical Impedance
Impedance of a linear circuit element with two terminals is the ratio of the complex sinusoidally varying voltage applied across the terminals to the complex current that flows in response.
Electrical Insulation
A material used to prevent the leakage of electricity from a conductor and to provide mechanical spacing or support as protection against accidental contact with the conductor.
Electrical Length
Physical length expressed in terms of the wavelength of a signal for the medium in which the component or structure is situated.
Electrical Resistance
The ability of a material to oppose the flow of an electric current, converting electrical energy into heat.
Electrical Screen
A metal shield which isolates a device from external fields.
Electrical Symbols
Graphic symbols used to illustrate the various electrical or electronic components of a circuit.
Improving the specular reflectivity of a metal surface by electrochemical dissolution.
Electrochemical Cell
A device that uses a redox reaction to produce electricity, or a device that uses electricity to drive a redox reaction in the desired direction.
Electrochemical Energy Storage
The storage of energy in a system such as a battery.
Electrochemical Gradient
The sum of the gradients of concentration and of electric charge of an ion across a membrane.
Electrochemical Potential
The energy required to maintain a separation of charge and of concentration across a membrane.
The study of the interchange of chemical and electrical energy.
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The deposition of a substance on an electrode by passing electric current through an electrolyte.
Device that moves electrons into or out of a solution by conduction.
Electrodynamic Meter Movement
A meter movement using fixed field coils and a moving coil; usually used in ammeters and wattmeters.
The study of phenomena associated with charged bodies in motion and varying electric and magnetic fields.
A meter using an electrodynamic movement to measure an electric current.
To form shaped objects by electro-deposition on a mould.
Electrokinetic Potential
Electric potential across all phase boundaries between solids and liquids, also known as the Zeta Potential.
Electroless Nickel Plating
An auto-catalytic chemical technique used to deposit a layer of nickel-phosphorus or nickel-boron alloy on a solid workpiece, such as metal or plastic.
An electrochemical device which works like a fuel cell in reverse and can split water into its constituent molecules, hydrogen and oxygen, by passing an electric current through it.
Changing the chemical structure of a compound using electrical energy.
A substance that dissociates fully or partially into ions when dissolved in a solvent, producing a solution that conducts electricity.
Electrolytic Capacitor
A type of capacitor that has a liquid or paste between the plates to increase its capacitance.
Electrolytic cell
A cell that uses electrical energy to produce a chemical change that would otherwise not occur spontaneously.
A magnet formed by an inductor having current flow through it.
Electromagnetic Compatibility
The capability of different electrical systems to coexist in the electromagnetic environment without causing or being subjected to interference.
Electromagnetic Coupling
The transfer of electromagnetic energy from one circuit or system to another circuit or system.
Electromagnetic Energy
The energy stored in an electromagnetic field.
Electromagnetic Environment
The signal and noise complex within which communications-electronics devices are operated.
Electromagnetic Field
Electric and magnetic forces that exist in a physical volume.
Electromagnetic Force
A force with infinite range which acts between objects according to their charge.
Electromagnetic Induction
The production of a voltage in a coil because of a change in the number of magnetic lines of force passing through the coil.
Electromagnetic Interaction
The interaction due to electric charge; this includes magnetic effects that have to do with moving electric charges.
Electromagnetic Interference
Any induced, radiated, or conducted electrical emission, disturbance, or transient that causes undesirable responses, degradation in performance, or malfunctions of any electrical or electronic equipment, device, or system.
Electromagnetic Pulse
The generation and radiation of a very narrow and very high-amplitude pulse of electromagnetic noise.
Electromagnetic Radiation
The emanation of an electromagnetic field from a source through space.
Electromagnetic Spectrum
Complete range of wavelengths for electromagnetic waves. These include infared, ultraviolet, and all other types of electromagnetic radiation, as well as visible light.
Electromagnetic Weapon
Any device which can produce an electromagnetic field of such intensity that targeted items of electronic equipment experience either a soft or hard kill.
Electromagnetically Induced Transparency
A technique that makes normally opaque substances transparent to light by applying another source of light, such as a laser beam, that interferes with the opaque substance′s absorption of light.
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Converting electrical input into mechanical action.
Electromotive Force
The difference of potential produced by an electrical source to drive a current through an external electrical circuit.
Electromotive Series
The electrode potential of a material according to decreasing tendency to release electrons with hydrogen as zero.
The electron charge is 1.602x10-19 C
Electron Affinity
The measure of an atom′s tendency to gain an electron.
Electron Beam
The stream of electrons generated by the electron gun and accelerated by the accelerator guide.
Electron Beam Welding
A technique for joining materials in which components to be welded are heated by a concentrated beam of high-velocity electrons in a vacuum.
Electron Capture
A decay process in which an inner atomic electron is captured by the nucleus.
Electron Channelling Patterns
A pattern formed by the periodic backscattering of electrons by the specimen lattice in a SEM.
Electron Charge
e = 1.602x10-19 C
Electron Configuration
A list showing how many electrons are in each orbital or subshell.
Electron Flow
The direction in which electrons flow. This is from negative to positive - as electrons are negatively charged.
Electron Geometry
Structure of a compound based on the arrangement of its electrons.
Electron Gun
An electrode of a CRT that is equivalent to the cathode and control grid of conventional tubes.
Electron Microscope
A type of microscope that uses a particle beam of electrons to illuminate the specimen and produce a magnified image.
Electron Orbital Movement
The movement of an electron around the nucleus of an atom.
Electron Shell
A group of electrons which have a common energy level that forms part of the outer structure of an atom.
Electron Spin
Electrons have an intrinsic angular momentum that is similar to what would be observed if they were spinning.
Electron Spin Pair
Two electrons with opposite spins, usually occupying the same orbital.
Electron Volt
Unit of energy of moving particles. Given by the kinetic energy acquired by an electron losing one volt of potential.
For an atom, having a tendency to accept valence electrons; also a term to describe non-metallic elements.
Measure of a substances' ability to attract electrons.
Electronic Control Unit
A generic term for any embedded system that controls one or more of the electrical systems or subsystems in a motor vehicle.
Electronic Counter-Countermeasures
Actions taken to insure friendly effective use of the electromagnetic spectrum despite the enemy's use of electronic warfare.
Electronic Countermeasures
Actions such as active electronic jamming taken to prevent, degrade or reduce effective use of the electromagnetic spectrum by an enemy, in electronic warfare.
Electronic Filter
Any of various electric, electronic, acoustic, or optical devices used to reject signals, vibrations, or radiation of certain frequencies while passing others.
Electronic Frequency Counter
An instrument that counts the number of cycles occurring during a precise time interval.
Electronic Jamming
An electronic countermeasure that is the deliberate radiation, re-radiation, or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices, equipment, or systems.
Electronic Structure
The distribution of electrons in the material and the energies related to changes in this distribution.
Electronic Warfare
Military action involving the use of electromagnetic energy to determine, exploit, reduce or prevent hostile use of the electromagnetic spectrum and action which retains friendly use of the electromagnetic spectrum.
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Electron-Positron Annihilation
When an electron and its anti-particle, a positron, collide, they annihilate emitting a pair of gamma-ray photons each with an energy of 511 keV.
A species that loves electrons.
The migration of colloidal particles dispersed in a fluid, under the influence of an electric field.
The study of the electrical properties of living tissue.
A process that produces a bright, shiny surface on a metal using an electrolytic cell under conditions that projections on the surface are dissolved faster than the smoother areas.
For an atom, having a tendency to release valence electrons.
A method for purifying a metal using electrolysis.
A process that uses electrolysis to selectively remove a constituent from solution.
Pertaining to electricity at rest, such as charges on an object.
Electrostatic Deflection
The method of deflecting an electron beam by passing it between parallel charged plates mounted inside a cathode-ray tube.
Electrostatic Field
The field of influence between two differently charged bodies.
Electrostatic Force
Force experienced by stationary electrically charged particles in an electric field; the force which binds electrons to a nucleus in an atom.
Electrostatic Induction
A modification in the distribution of electric charge on one material under the influence of an electric charge on a nearby object.
Electrostatic Interactions
Attractions between opposite charges or repulsions between like charges that grow stronger as the charges become closer to each other.
Electrostatic Machine
A generator which produces an electric charge by friction or electrostatic induction.
Electrostatic Meter Movement
A meter movement that uses the electrostatic repulsion of two sets of charged plates.
Electrostatic Sensitivity
The degree to which a component or device is susceptible to damage by electrostatic discharge.
Electrostatic Stress
An electrostatic field acting on an insulator, which produces polarization in the insulator and causes electrical breakdown if raised beyond a certain intensity.
Electrostatic Unit
A unit of electric charge that exerts a force of 1 dyne on another unit of charge at a distance of 1 centimeter in a vacuum (cgs).
Small changes in the dimensions of a dielectric when placed in an electric field.
The valence as determined by the electrons lost or gained by the elements reacting to form a compound.
The phenomenon of a change in viscosity due to the presence of charge on particles suspended in a solvent.
Electroweak Interaction
In the Standard Model, electromagnetic and weak interactions are related (unified).
An alloy of 75% gold and 25% silver along with small quantities of other metals such as copper.

A pure substance which cannot be broken down into simpler substances by chemical means.
Element Symbol
An international abbreviation for element names, usually consisting of the first one or two distinctive letters in element name.
A member of or an object in a set.
Elementary Charge
The electric charge on an electron particle.
Elementary Function
One of the functions: rational functions, trigonometric functions, exponential functions, and logarithmic functions.
Elementary Matrix
A matrix that is obtained by performing an elementary row operation on an identity matrix.
Elementary Particles
The particles which form the building blocks of atoms and those which carry energy.
Elementary Reaction
A reaction that occurs in a single step.
Elementary Step
Reaction mechanisms are broken down into elementary steps.
Vertical distance of a point on or affixed to the surface of the ground.
Elevation Angle
The angle between the horizon and a point above the local horizon in the celestial sphere, measured along the great circle that passes through both the zenith and the point in question.
Movable control surface, attached to the trailing edge of an aircraft tailplane to control pitching movements.
Movable control surfaces which act collectively as elevators, but differentially as ailerons.
That portion of the radio frequency spectrum from 30 to 3000 hertz.
A plane through a right angle cone.
A solid figure whose equation is x2/a2+y2/b2+z2/c2=1.
Elliptical Arch
Many mediaeval stone bridges were built with elliptical arches spanning rivers.
Elliptical Orbit
An orbit which describes an ellipse or oval shape.
A hard, durable and coarse grained wood. Used for ship building.
Increase in length which occurs before a metal is fractured, when subjected to stress.
The process of separating the finer particles of an earthy substance from the coarser and heavier by washing with water.