Electricity for public schools and colleges . the centre of a larger disc. Then, since the fixed and moveable portions were connectedand at one potential, and since there was no perceptible breakbetween them, it followed that with respect to the moveable por-tion of the one disc, and the central portion of the other fixeddisc that was opposite and parallel to the former, the assumptionsas to uniformity did hold. In fact, only the central portions ofthe discs were used. have the arrangement indicated. The twoand the formula applies to the moveableportion/of the one plate andthe portion opposite
Electricity for public schools and colleges . the centre of a larger disc. Then, since the fixed and moveable portions were connectedand at one potential, and since there was no perceptible breakbetween them, it followed that with respect to the moveable por-tion of the one disc, and the central portion of the other fixeddisc that was opposite and parallel to the former, the assumptionsas to uniformity did hold. In fact, only the central portions ofthe discs were used. have the arrangement indicated. The twoand the formula applies to the moveableportion/of the one plate andthe portion opposite to thisof the other fixed plate. Themoveable portion f is at theend of a light lever whosefulcrum, or axis of suspension,is a wire m n. At the freeend of this lever is a hair /;this is viewed by a lens, andserves to indicate when theplate/is flush with the guard-plate h required to keep/in its place gives us F. Whence,by knowing the dimensions, &c., of the instrument, we measure(V, -V2). In the figure we plates are // // and. CH. X. ELECTROSTATIC FOTENTIAL 15: § ;^^. Sir William Thomsons Quadrant Electrometer.—The principle of the quadrant electrometer can be illustrated by theBohnenbergers electroscope. If the gold-leaf were kept at a constant high potential, whilethe difference of potential between the two knobs was the variablequantity, then the amount of deflexion of the gold-leaf would in-dicate the difference of potential between the two knobs. The next figure gives a sketch, taken looking down directlyfrom above, of the essential parts of the quadrant electrometer. Let us take a cylmdrical box of thin brass about one inch highand about five inches in diameter. Let us cut this into foursectors as indicated in the figure,and let us connect opposite sec-tors respectively by wire, and sup-port all four sectors on insulatingglass legs. We thus have four hollowbrass sectors ; in the interior ofeach of which, as an approxi-mately closed vessel, there is,excepting
Size: 1800px × 1389px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpubl, booksubjectelectricity
