Our work concerns electrostatic forces; force fields that surround us everywhere.
That's true but the electrostatic attraction is something we're just beginning to understand.
What's this negative-positive business and electrostatic field?
Electrostatic fields come from a voltage gradient and can exist when charge carriers are stationary.
The unit to which they are ordinarily referred is I electrostatic unit of electricity per cubic metre of air.
Taking i volt equal 1/300 of an electrostatic unit, we find M =0.000265.
The charge on the earth itself has its surface density given by v = - (I/47r) X125 volts per metre, =0.000331 in electrostatic units.
From this we deduce for the charge p per cubic centimetre (I/41r)Xio-5 (volt/cm 2), or 2.7 X 101 electrostatic units.
In the Nalder ohmmeter the electrostatic principle is employed.
It has in fact been found, with the very great precision of which optical experiment is capable, that all terrestrial optical phenomenareflexion, refraction, polarization linear and circular, diffraction - are entirely unaffected by the direction of the earth's motion, while the same result has recently been extended to electrostatic forces; and this is our main experimental clue.
There are methods of measuring electrical power by means of electrostatic voltmeters, or of quadrant electrometers adapted for the purpose, which when so employed may be called electrostatic wattmeters.
Sumpner in 1891, an electrostatic voltmeter is employed to measure the fall of potential V 1 down any inductive circuit in which it is desired to measure the power absorption, and also the volt-drop V2 down an inductionless resistance R in series with it, and also the volt-drop V3 down the two together.
Voltmeters may be divided into two classes, (a) electrostatic, (b) electrokinetic.
Electrostatic voltmeters are based on the principle that when two conductors are at different potentials they attract one another with a force which varies as the square of the potential difference (P. D.) between them.
One large class of electrostatic voltmeters consists of a fixed metal plate or plates and a movable plate or plates, the two sets of plates forming a condenser (see Leyden Jar).
Utilizing this principle many inventors have devised forms of electrostatic voltmeter.
- Lord Kelvin's Multicellular Electrostatic Voltmeter.
In other types of electrostatic instruments the movable system rotates round a horizontal axis or rests upon knife edges like a scale beam; in others again the movable system is suspended by a wire.
Electrostatic voltmeters are now almost entirely used for the measurement of high voltages from 2000 to 50,000 volts employed in electrotechnics.
Hot wire voltmeters, like electrostatic voltmeters, are suitable for use with alternating currents of any frequency as well as with continuous currents, since their indications depend upon the heating power of the current, which is proportional to the square of the current and therefore to the square of the difference of potential between the terminals.
- Round Dial Kelvin Multicellular Electrostatic Voltmeter, 5-in.
Like the corresponding ammeters, they have the great advantage that the scales are equidivisional and that there is no dead part in the scale, whereas both the electrostatic and electrothermal voltmeters, above described, labour under the disadvantage that the scale divisions are not equal but increase with rise of voltages, hence there is generally a portion of the scale near the zero point where the divisions are so close as to be useless for reading purposes and are therefore omitted.
This measurement is applicable to the measurement of high potentials, either alternating or continuous, provided that in the case of alternating currents the high resistance employed is wound non-inductively and an electrostatic voltmeter is used.
It is always an advantage, if possible, to employ an electrostatic voltmeter for measuring potential difference if it is necessary to keep the voltmeter permanently connected to the two points.
Electrostatic instruments, however, take up no power and hence cost nothing for maintenance other than wear and tear of the instrument.
(iii.) The instrument should have no temperature correction; this is a good quality of electrostatic instruments, but in all voltmeters of the electrokinetic type which are wound with copper wire an increase of one degree centigrade in the average temperature of that wire alters the resistance by 0.4%, and therefore to the same extent alters the correctness of the indications.
Electrostatic voltmeters are also liable to have their indications disturbed by electrification of the glass cover of the instrument; this can be avoided by varnishing the glass with a semi-conducting varnish so as to prevent the location of electrostatic charges on the glass.
The separation also sets up electrostatic forces, which increase until they are strong enough to drag the slower moving ions along faster, and to retard the naturally faster ions till they travel at the same rate.
ELECTRICAL (or [[Electrostatic) Machine]], a machine operating by manual or other power for transforming mechanical work into electric energy in the form of electrostatic charges of opposite sign delivered to separate conductors.