CHAFFER II 

 QUANTITY OF ELECTRIFICATION 



Use of the electroscope to indicate equality of charge The two electriii 

 (ions always appear or disappear in equal amounts whether the electritir i 

 tion is by friction, by conduction, by induction, or by supply from current 

 Electrification resides only on the outside surface of a conductor unless 

 it contains insulated charged bodies An inflated charged conductor 

 inside a hollow conductor induces an equal and harge on tli- 



inside and an equal like charge on the outbid- Imagined construction 

 of multiples and submultiples of an arbitrary unit of charge Imagined 

 method of measuring any charge in terms of this unit. 



WE shall now describe a series of experiments, some illustrating 

 the general laws of the production and distribution of elect ri; 

 tion, and others showing that we may make definite and eon>i>tent 

 measurements of quantity of electrification. 



Use of the electroscope to indicate equality of 



charge. If a deep and Harrow metal ves.sel, such as an ordinary 

 round tin canister, is placed on the upper table of a gold-leaf electro* 

 scope, it may be used to detect a very .slight charge of electri- 

 fication on a body, by the introduction of the botlv \\ithin the can. 

 It is not necessary to communicate any of the charge to the can, 

 for it will act inductively, calling up an opposite- charge on the 

 inside of the can and sending a like charge to the gold leaves.* 



As the body is being lowered within the can the divergen 

 the leaves rapidly increases at first, but soon it approaches a limit, 

 which it does not exceed, and the leavo remain practically !i 

 however the body be moved about within the can, so long a> it 

 does not come near the open top. 



If the can be closed by a lid with only a small hole for the 

 insulating holder of the body to pass through, the body may IHJ 

 brought quite close to the top, without change in the divergence 

 of the leaves. Thus a change in the position of a charged bodv 

 within a closed can does not affect the indications of an electro- 

 scope connected with the outside of the can. This result, which is 



* In tin- experiments described in thi> rhapti-r tin- gold-leaf electron o|.- may 

 be replinvd by tin- Quadrant Klectrom.-ter du.M/ribed <>u p. 87, the ran i 

 insulated and connected with one pair of quadrants. Much i:r-:itT M-n.-itiveness 

 is thus obtained, but the gold-leaf elect roM-ope may be made Hittirieiitly sensitive 

 for purposes of demonstration bv briniriiii: tin- >id.- plat- s nearer the leaves, ami it 

 is much more easily used than the Quadrant Electrometer. 



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