electro-, electr-, electri-

The quantity of electrical charge which repels an equal charge at a poiont in a vacuum at a distance of one centimeter with a force of one dyne.

1. A system of electrical units, based on the centimeter, gram, and second, in which a unit electric charge is by definition such that two units of the same sign placed one centimeter apart in vacuo (vacuum) will repel each other with a force of one dyne.

Units in the system are usually characterized by the prefix stat-, as statampere, statvolt, etc.

2. A centimeter-gram-second system of electric and magnetic units in which the unit of charge is that charge which exerts a force of one dyne on another unit charge when separated from it by a distance of one centimeter in a vacuum.

Other units are derived from this definition by assigning unit coefficients in equations relating electric and magnetic quantities.

1. A rule stating that in a stable state, valence (combining power) of negatively charged atoms equals the total strength of the bonds that they have formed with nearby positively charged ions.
2. A concept that in a stable ionic structure, the valence of each anion, with changed sign, equals the sum of the strengths of its electrostatic bonds to the adjacent cations or atoms or groups of atoms with one or more positive or negative electric charges.

1. An instrument that measures voltage according to the degree of attraction or repulsion between charged bodies.
2. A voltmeter which works by measuring the force exerted between stationary electric charges which is usually graduated in volts or kilovolts.
3. A voltmeter in which the voltage to be measured is applied between fixed and movable metal vanes.

The resulting electrostatic force deflects or turns the movable vane against the tension of a spring.

An instrument designed to measure high voltages in watts by means of electrostatic forces.

The wave motion of a plasma (an electrically conductive fluid) in which restoring forces are primarily electrostatic.

The principle of electron-beam convergence through the use of an electrostatic field.

1. The study of the phenomena associated with electric charges at rest.
2. The study of electric fields produced by stationary source charges or, more precisely, a constant charge density at each point.
3. A branch of physics dealing with electric charges at rest and with objects charged with electricity and constant-intensity electric fields.

1. A process in which an electrostatically charged printing plate is exposed so that the resulting positive image attracts a negatively charged resin.
2. The process of recording and reproducing visible patterns with the formation and utilization of inactive electrostatic charge patterns.
3. A generic term covering all processes involving the forming and use of electrostatic charged patterns for recording and reproducing images.

This field of recording and reproducing images is divided into electrophotography and electrography.

1. An electrical instrument that amplifies or records the respiratory and cardiac sounds of the chest.
2. A very sensitive, electrically operated instrument used to record sounds of the heart.

This is an instrument which gives doctors a high-fidelity record of heart sounds so faint they can't be heard by human ears even with the aid of a physician's stethoscope.

An electrically amplified stethoscope consisting of a microphone and audio amplifier feeding headphones which is used for detection and the study of sounds arising within the human body.

1. The use of electric current to stimulate a tissue; such as, muscle, nerve, or bone.

In the latter case, the stimulation is used experimentally to facilitate and to hasten the healing of fractures.

2. The application of electric current to stimulate bone or muscle tissue for therapeutic purposes; such as, the facilitation of muscle activation and muscle strengthening.

1. An electroencephalogram (tracing of the electric impulses of the brain) showing differences in electric potential recorded at various levels of the corpus striatum (either of two gray and white, striated bodies of nerve fibers located in the lower lateral wall of each cerebral hemisphere).
2. A depth recording obtained from electrodes inserted into the corpus striatum (a mass of striped gray and white nervous tissue in each hemisphere of the brain).

A transducer (any instrument; such as, a microphone or electric motor, that converts one form of energy into another) which depends on the production of an elastic strain in certain symmetric crystals when an electric field is applied, or, conversely, which produces a voltage when the crystal is deformed.

1. The classic deforming of a dielectric material when it is stressed by an electric field.
2. A form of elastic deformation of a dielectric induced by an electric field, associated with those components of strain that are independent of reversal of field direction, in contrast to the piezoelectric effect.
3. The change in dimensions which occurs in some dielectric materials when they are placed in an electric field.
4. An activity similar to piezoelectricity, but electrostrictive ceramics expand according to the square of the voltage whereas piezoelectric materials expand linearly.

Electrostrictive materials present less hysteresis (delayed response) than piezoelectric materials, but they are difficult to use at very low voltages.