The Standard Electrical Dictionary Part 45

163 STANDARD ELECTRICAL DICTIONARY.

Current, Foucault.

A current produced in solid conductors, and which is converted into heat (Ganot). These currents are produced by moving the conductors through a field, or by altering the strength of a field in which they are contained. They are the source of much loss of energy and other derangement in dynamos and motors, and to avoid them the armature cores are laminated, the plane of the laminations being parallel to the lines of force. (See Core, Laminated.)

The presence of Foucault currents, if of long duration, is shown by the heating of the metal in which they are produced. In dynamo armatures they are produced sometimes in the metal of the windings, especially if the latter are of large diameter.

Synonyms--Eddy Currents--Local Currents--Parasitical Currents.

Current, Franklinic.

In electro-therapeutics the current produced by a frictional electric machine.

Current, Induced.

The current produced in a conductor by varying the conditions of a field of force in which it is placed; a current produced by induction.

Current Induction.

Induction by one current on another or by a portion of a current on another portion of itself. (See Induction.)

Current Intensity.

Current strength, dependent on or defined by the quant.i.ty of electricity pa.s.sed by such current in a given time. The practical unit of current intensity is the ampere, equal to one coulomb of quant.i.ty per second of time.

Current, Inverse Induced.

The current induced in a conductor, when in a parallel conductor or in one having a parallel component a current is started, or is increased in strength. It is opposite in direction to the inducing current and hence is termed inverse. (See Induction, Electro-magnetic.) The parallel conductors may be in one circuit or in two separate circuits.

Synonyms--Make-induced Current--Reverse-induced Current.

Current, Jacobi's Unit of.

A current which will liberate one cubic centimeter of mixed gases (hydrogen and oxygen) in a water voltameter per minute, the gases being measured at 0? C. (32? F.) and 760 mm. (29.92 inches) barometric pressure. It is equal to .0961 ampere.

Current, Joint.

The current given by several sources acting together. Properly, it should be restricted to sources connected in series, thus if two battery cells are connected in series the current they maintain is their joint current.

Current, Linear.

A current pa.s.sing through a straight conductor; a current whose path follows a straight line.

164 STANDARD ELECTRICAL DICTIONARY.

Current, Make and Break.

A succession of currents of short duration, separated by absolute cessation of current. Such current is produced by a telegraph key, or by a microphone badly adjusted, so that the circuit is broken at intervals.

The U. S. Courts have virtually decided that the telephone operates by the undulatory currents, and not by a make and break current. Many attempts have been made to produce a telephone operating by a demonstrable make and break current, on account of the above distinction, in hopes of producing a telephone outside of the scope of the Bell telephone patent.

[Transcriber's note: Contemporary long distance telephone service is digital, as this item describes.]

Current-meter.

An apparatus for indicating the strength of current. (See Ammeter.)

Current, Negative.

In the single needle telegraph system the current which deflects the needle to the left.

Current, Nerve and Muscle.

A current of electricity yielded by nerves or muscles. Under proper conditions feeble currents can be taken from nerves, as the same can be taken from muscles.

Current, Opposed.

The current given by two or more sources connected in opposition to each other. Thus a two volt and a one volt battery may be connected in opposition, giving a net voltage of only one volt, and a current due to such net voltage.

Current, Partial.

A divided or branch current. A current which goes through a single conductor to a point where one or more other conductors join it in parallel, and then divides itself between the several conductors, which must join further on, produces partial currents. It produces as many partial currents as the conductors among which it divides. The point of division is termed the point of derivation.

Synonym--Derived Current.

Current, Polarizing.

In electro-therapeutics, a constant current.

Current, Positive.

In the single needle telegraph system the current which deflects the needle to the right.

Current, Pulsatory.

A current of constant direction, but whose strength is constantly varying, so that it is a series of pulsations of current instead of a steady flow.

Current, Rectified.

A typical alternating current is represented by a sine curve, whose undulations extend above and below the zero line. If by a simple two member commutator the currents are caused to go in one direction, in place of the sine curve a series of short convex curves following one another and all the same side of the zero line results. The currents all in the same direction, become what is known as a pulsating current.

Synonym--Redressed Current.

165 STANDARD ELECTRICAL DICTIONARY.

Current, Rectilinear.

A current flowing through a rectilinear conductor. The action of currents depending on their distance from the points where they act, their contour is a controlling factor. This contour is determined by the conductors through which they flow.