The Standard Electrical Dictionary Part 169

Its disadvantages are thus summarized by Ayrton. It absorbs a good deal of energy; it cannot be constructed for small potential differences, as the wire cannot be made thicker, as it would make it more sluggish; there is vagueness in the readings near the zero point and sometimes inaccuracy in the upper part of the scale.

Volts, Lost.

The volts at the terminals of a dynamo at full load fall short of their value on open circuit. The difference of the two values are termed lost volts.

Voltmeter, Electrostatic.

A voltmeter based on the lines of the quadrant electrometer. It includes two sets of quadrants, each oppositely excited by one of the two parts, whose potential difference is to be determined. They attract each other against a controlling force as of gravity.

One form has the two sets poised on horizontal axes, bringing the parts so that the flat quadrants move in vertical planes.

In another form a number of quadrants are used in each set, the members of the two sets alternating with each other. One set is fixed, the others move and carry the index.

Vulcanite.

Vulcanized india rubber which by high proportion of sulphur and proper vulcanization has been made hard. It is sometimes distinguished from ebonite as being comparatively light in color, often a dull red, while ebonite is black. For its electrical properties see Ebonite.

Both substances have their defects, in producing surface leakage.

Washing with weak ammonia, or with dilute soda solution, followed by distilled water, is recommended for the surface, if there is any trouble with surface leakage. It may also be rubbed over with melted paraffine wax.

572 STANDARD ELECTRICAL DICTIONARY.

W.

(a) A symbol or abbreviation for watt.

(b) A symbol or abbreviation for work.

(c) A symbol or abbreviation for weight.

Wall Bracket.

A telegraph bracket to be attached to the external walls of buildings to which wires are attached as they come from the poles to reach converters, or for direct introduction into a building.

Wall Sockets.

Sockets for incandescent lamps constructed to be attached to a wall.

Ward.

Direction in a straight line; a term proposed by Prof. James Thompson.

The words "backward" and "forward" indicate its scope.

Water.

A compound whose molecule consists of two atoms of hydrogen and one atom of oxygen; formula, H2 O.

Its specific gravity is 1, it being the base of the system of specific gravities of solids and liquids.

If pure, it is almost a non-conductor of electricity. If any impurity is present it still presents an exceedingly high, almost immeasurable true resistance, but becomes by the presence of any impurity an electrolyte.

Water Equivalent.

In a calorimeter of any kind the weight of water which would be raised as much as is the calorimeter with its contents by the addition of any given amount of heat received by the calorimeter.

Waterproof Lamp Globe.

An outer globe for incandescent lamps, to protect them from water.

Watt.

(a) The practical unit of electric activity, rate of work, or rate of energy. It is the rate of energy or of work represented by a current of one ampere urged by one volt electro-motive force; the volt-ampere.

It is the a.n.a.logue in electricity of the horse power in mechanics; approximately, 746 watts represent one electric horse power.

Ohm's law, taken as C = E/R, gives as values for current, C and E/R, and for electro- motive force C R. In these formulas, C represents current strength, R represents resistance and E represents electro-motive force.

Then a watt being the product of electro-motive force by current strength, we get the following values for rate of electric energy, of which the watt is the practical unit: (1) E2/R -- (2) C*E -- (3) C2 * R.

The equivalents of the watt vary a little according to different authorities. Ayrton gives the following equivalents: 44.25 foot pounds per minute--.7375 foot pounds per second--1/746 horse power. These values are practically accurate. Hospitalier gives .7377 foot pounds per second. Hering gives .737324 foot pounds per second, and 1000/745941 horse power.

573 STANDARD ELECTRICAL DICTIONARY.

It is equal to 1E7 ergs per second.

Synonym--Volt-ampere.

(c) It has been proposed to use the term as the unit of energy, instead of activity or rate of energy (Sir C. W. Siemens, British a.s.sociation, 1882); this use has not been adopted and may be regarded as abandoned.

[Transcriber's note; Watt is a unit of POWER--energy per unit of time.]

Watt-hour.

A unit of electric energy or work; one watt exerted or expended for one hour.

It is equivalent to : 866.448 gram-degrees C. (calories) 2654.4 foot lbs.

3600 watt-seconds or volt-coulombs.

60 watt-minutes.

Watt-minute.

A unit of electric energy or work; one watt exerted or expended for one minute.

It is equivalent to 14.4408 gram-degrees C. (calories), 44.240 foot pounds, 60 watt seconds or volt-coulombs, 1/60 watt hour.