electro-, electr-, electri-

Four equations, formulated by James Clerk Maxwell, that together form a complete description of the production and interrelation of electric and magnetic fields.

The statements of these four equations are as follows:

1. Electric field diverges from electric charge.
2. There are no isolated magnetic poles.
3. Electric fields are produced by changing magnetic fields.
4. Circulating magnetic fields are produced by changing electric fields and by electric currents.

Maxwell based his description of electromagnetic fields on these four statements.

An electrosurgical instrument used for the prostate gland.

Continued electrical rhythmicity of the heart in the absence of effective mechanical function.

It might be caused by the uncoupling of ventricular muscle contraction from electrical activity or it might be a result of cardiac damage with respiratory failure and cessation of cardiac venous return.

1. A mechanism for measuring electric current passing through a coil by the deflection of a magnetic needle inside the coil.
2. A device for measuring an electric charge by the movement of a vane suspended on a wire between metal quadrants.

The charge is introduced on the vane and quadrants in such a way that there is a proportional twist to the wire.

1. An electrode in the electric potential is generated by the relative proportions of quinone (a class of aromatic compounds found widely in plants, especially the yellow crystalline form used in making dyes, tanning hides, and photography) and quinhydrone (dark green, crystalline, slightly water-soluble solid used in a solution, together with a platinum wire, as an electrode) which are present.
2. One of several oxidation-reduction electrode's in which the ratio of the two forms (quinone-quinhydrone), determined by the hydrogen ion concentration, sets up a potential that can be measured and converted to a pH value (fails above pH 8).
3. Quinhydrone electrode is a redox electrode (inert electrode; such as, platinum, gold, carbon) used for measuring pH (measure of the acidity/alkalinity of a solution).

An inert metal (usually platinum) is immersed into the solution to be analyzed and a small amount of quinhydrone crystals is added to the solution.

Quinhydrone is slightly soluble in water, dissolving to form a mixture of two substances, with each of the two substances easily oxidized or reduced to the other.

The potential at the inert electrode depends on the ratio of the concentrations of two substances, which, in turn, depends on the pH.

An electrode used to measure electric potential changes in body tissue.

When used for recording, two electrodes must be used: the exploring electrode and the reference electrode.

1. A chemical electrode whose cell potential remains fixed and against which an indicator electrode is compared.

The most common reference electrode is the silver electrode or silver chloride electrode.

2. An electrode the placement of which is remote from the source of recorded activity, so that it is presumed to be at either a negligible or a constant potential.

1. An electrode that derives its potential to unit charges of a reversible nature, in contrast to electrodes used in electroplating and destroyed during their use.
2. An electrode; such as, the silver/silver chloride electrode in which the electrochemical reaction is reversible, which results in a low resistance to direct current.

An electrode reaction is considered reversible in the "electrochemical sense" if the reaction is fast, that is, if the exchange current density of the electrode reaction is large.

In contrast, in the "chemical sense", reversibility indicates that the reaction can proceed both in forward and backward (reverse) directions.

An intracardiac electrogram which is obtained by placing electrodes in the apex of the right ventricle.

It is used in mapping ventricular arrhythmias.

An intracardiac electrogram that is obtained by placing electrodes in the right ventricle.

It is used to asses ventricular activities and responses to stimuli.

1. A variant of crossed electrophoresis in which the medium contains only one antibody.

Test substances are driven directly into the medium which contains the antibody, forming rocket-shaped (inverted V) trails of precipitation.

2. Electrophoresis in which antigen migrates from a well through agar gel containing antiserum, forming cone-shaped (rocket) precipitin bands.

The area under the cone is used to calculate the amount of antigen.

One of two practical reference electrodes, used with a mercurous chloride (calomel) paste in pH (measure of the acidity or alkalinity of a solution) and other potentiometric (voltage-measuring) instruments. The other is the silver/silver chloride electrode.

The calomel (mercury compound) electrode has been the standard secondary reference electrode used in the laboratory since the introduction of the pH electrode.

The usual electrocardiogram which plots voltage versus time, as distinguished from the vectorcardiogram, which plots voltage versus phase.

An electrode which is placed on or just below the surface of the scalp.

This is the most common type used in electroencephalography.

The technique using a scanning electron microscope on a specimen.