. Conduction of electricity through gases and radio-activity; a text-book with experiments . box, fixedin a horizontal position and having a small vertical centralhole through it, is divided by very narrow saw cuts into fourquadrants as indicated in Fig. 6. Each of these quadrantsrests on an insulating support. Within these quadrants, mid-way between the upper and lower plates, is suspended by avery light fiber suspension a flatdumbbell-shaped needle made ofaluminium or other light con-ducting substance. The diag-onally opposite quadrants areconnected together as shown inFig. 6. If the needle
. Conduction of electricity through gases and radio-activity; a text-book with experiments . box, fixedin a horizontal position and having a small vertical centralhole through it, is divided by very narrow saw cuts into fourquadrants as indicated in Fig. 6. Each of these quadrantsrests on an insulating support. Within these quadrants, mid-way between the upper and lower plates, is suspended by avery light fiber suspension a flatdumbbell-shaped needle made ofaluminium or other light con-ducting substance. The diag-onally opposite quadrants areconnected together as shown inFig. 6. If the needle is hungsymmetrically with regard tothe quadrants as shown in thediagram, and if it is charged toa positive potential and a differ-ence of potential be established between the two pairs ofquadrants, the needle will be attracted by one pair and repelledby the other pair and will rotate in a horizontal plane. Theamount of attraction and repulsion will depend upon the dif-ference of potential between the quadrants and the potentialof the needle and consequently the amount of rotation of the. Fig. 6. IO APPARATUS AND GENERAL METHODS needle will depend upon these factors and also upon thetorsional rigidity of the suspension. The remaining parts vary in different types of the older forms and even in some of the modern types ofinstrument the needle is connected to a small condenser usuallyin the form of a Leyden jar to increase the capacity of theneedle, so that any small leakage of the charge from the needlewill not alter its potential as much as if its capacity weresmall. Connection between the needle and inside coating ofthe Leyden jar is made by allowing the central rod of theneedle to extend below the quadrants and dip into sulphuricacid contained in the Leyden jar. The acid also acts as a drying
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Keywords: ., bookcentury1900, bookdecade1900, bookid, booksubjectradioactivity
