electro-, electr-, electri-

(Greek > Latin: electric, electricity; from amber, resembling amber, generated from amber which when rubbed vigorously [as by friction], produced the effect of static electricity)

Electronics in our lives consists of numerous tools

Equipment which we use everyday relies on electronics to function including calculators, car controls, cameras, washing machines, medical scanners, mobile telephones, radar systems, computers; as well as many other applications or devices which are listed in this unit.

electromagnetic interference, EMI
1. Interference in a circuit caused by the radiation of an electric or magnetic field or the operation of a nearby electric motor; for example, the disturbance on a television set.
2. The harmful impairment of a desired electromagnetic signal by an electromagnetic disturbance.
3. Electromagnetic phenomena which, either directly or indirectly, can contribute to a degradation in the performance of an electronic receiver or system.

The terms radio interference, radio-frequency interference, noise, emi, and rfi have all been used at various times in reference to the same definition context.

4. An electrical, or electromagnetic, disturbance in a system caused by natural phenomena (lightning), low-frequency waves from electromechanical devices, or high-frequency waves from chips and other electronic devices; such as, radar, radio and TV signals, motors with brushes, and power lines.

Such electromagnetic disturbances can induce unwanted voltages in electronic circuits, damage components, and cause malfunctions.

Shields, filters, and transient suppressors are used in an effort to protect electronics from electromagnetic interferences.

electromagnetic lens
1. An electron lens in which electron beams are focused by an electromagnetic field.
2. An electromagnet designed to produce a suitably shaped magnetic field for the focusing and deflection of electrons or other charged particles in electron optical instruments.
3. An electron lens consisting of a homogeneous axial electric field and a magnetic field, used in high-quality image tubes for high Modulation Transfer Function (MTF, a measurement of monitor sharpness) and small geometrical distortion requirements.
electromagnetic library security system
A security system that uses magnetic strips in objects that are read by a scanner in an antenna or a sensitizer/desensitizer.
electromagnetic log, EM log
1. An instrument used to measure and to record the movement rate of a vessel through water, having an electromagnetic sensing element that hangs from the vessel (craft designed for water transportation) and which produces a voltage that is directly proportional to the vessel's speed.
2. A log containing an electromagnetic sensing element extended below the hull of a vessel or ship.

This device produces a voltage directly proportional to the speed through the water.

electromagnetic logging, electromagnetic well logging
1. A system that measures and records electromagnetic currents within a formation that is being drilled.
2. A method of well logging in which a transmitting coil sets up an alternating electromagnetic field, and a receiver coil, placed in the drill hole above the transmitter coil, that measures the secondary electromagnetic field induced by the resulting eddy currents within the formation.
electromagnetic mass
1. The mass of a moving charge whose kinetic energy appears to account for the discrepancy between the total field energy and the field energy of a purely static electric field.
2. The contribution to the mass of an object from its electric and magnetic field energy.
electromagnetic mirror
1. An area or surface that is capable of reflecting electromagnetic waves.
2. A surface or a region capable of reflecting radio waves; such as, one of the ionized layers in the upper atmosphere.
electromagnetic mixing
1. The process of mixing molten metals or alloys by applying an electromagnetic field to produce eddies (movements in streams of fluids in which the currents double back on themselves causing miniature whirlpools).
2. The mixing of molten alloys by exposing the melt to a strong magnetic field while passing direct electrical current between electrodes at opposite ends of the crucible.

The stirring action results from an interaction of the magnetic field of the current-carrying molten alloy with the external transverse magnetic field.

electromagnetic moment, magnetic moment
1. A measure of the magnetic strength of a magnet or a current-carrying coil, expressed as the torque produced when the magnet or coil is set with its axis perpendicular to unit magnetic flux density which is measured in ampere meters squared.
2. The magnetic moment of a current-carrying coil, equal to the product of the current, the number of turns, and the area of the coil.
3. The vector magnetic moment of a current-carrying coil, equal to the product of the current, the number of turns, and the area of the coil.

The direction is given by the right-hand rule (right hand rule) or hand rule, which refers to a current-carrying wire where the rule is that if the fingers of the right hand are placed around the wire so that the thumb points in the direction of current flow, the fingers will be pointing in the direction of the magnetic field produced by the wire.

electromagnetic noise, radiation noise
1. Noise in a communications system resulting from undesired electromagnetic radiation.
2. Any undesired electromagnetic disturbance.
electromagnetic oscillograph
1. An oscillograph that records signal waveforms by means of a moving-coil galvanometer or it is also known as a device for recording the wave-forms of changing currents, voltages, or any other quantity that can be translated into electric energy; such as, sound waves.
2. An oscillograph in which the recording mechanism is controlled by a moving-coil galvanometer; such as, a direct-writing recorder or a light-beam oscillograph (device for making a record of the wave forms of fluctuating voltages or currents).
electromagnetic phenomena
The term electromagnetic is used to describe the combined electric and magnetic fields which are associated with movements of electrons through conductors.

The process includes the combined electrical and magnetic effects exhibited by and used by equipment, apparatus, and instruments; and, in terms of radiation, to describe the radiation which is associated with a periodically varying electric and magnetic field that is traveling at the speed of light; such as, light waves, radio waves, X-rays, gamma radiation, etc.

electromagnetic plane wave, TE wave
A transverse electric wave, transverse electromagnetic wave, or transverse magnetic wave.

A transverse electric wave and a transverse magnetic wave are electromagnetic waves in which the magnetic field vectors are every where perpendicular to the directions of propagation.

electromagnetic pollution, EMI
The effects of electromagnetic interference produced by human-made apparatus.

The seriousness of this interference ranges from annoying interference that affects a radio or television channel to interference which causes failure of an important communication channel or a cardiac pacemaker.

electromagnetic potential
1. The electrostatic scalar potential plus the magnetic vector potential.
2. A collective name for a scalar potential, which reduces to the electrostatic potential in a time-independent system, and the vector potential for the magnetic field.

The electric and magnetic fields can be written in terms of these potentials.

The references or sources of information for compiling the words and definitions in this unit are listed at this Electronic Bibliography page or specific sources are indicated when they are appropriate.

A cross reference of word units that are related, directly and/or indirectly, with "electricity": galvano-; hodo-; ion-; piezo-; -tron; volt; biomechatronics, info; mechatronics, info.