. The Bell System technical journal . )emits eIectron>. Vtw this reason it is often known as the photoelectricmethod. alth()iii;ii ihc suhslitulion of one kind of receixer for anotheris iinl ii> niii^t (li^tiiuiis I ili,;i ic. .\ target made of the sub-stance to i>e sluilied is in in a I iilic, ii|)p(>sili a source of electrons(generalh a filament for lIuTiniunic rmi^simi); the photosensitiveelectrode is placed somewhere in the tui)e where w!iale\er ra\s areexcited at the surface of the target will fall direclh upon it. It is all-important to i)rotect this electro
. The Bell System technical journal . )emits eIectron>. Vtw this reason it is often known as the photoelectricmethod. alth()iii;ii ihc suhslitulion of one kind of receixer for anotheris iinl ii> niii^t (li^tiiuiis I ili,;i ic. .\ target made of the sub-stance to i>e sluilied is in in a I iilic, ii|)p(>sili a source of electrons(generalh a filament for lIuTiniunic rmi^simi); the photosensitiveelectrode is placed somewhere in the tui)e where w!iale\er ra\s areexcited at the surface of the target will fall direclh upon it. It is all-important to i)rotect this electrode from electrons and inns, negativeor positi\e. proceeding from target, lilanuiit, or anxwhere else. soMF. \ . IX ri[ysics-~iii 285 Isually tlu- iIiTtnulc is siretiKHl hy a family of gau/cs, with tlieirpotentials ailjustfd as is iiuliiatcd in Fij;. o (with the paths of intrudingions of lK)th signs, ini-liuling those excited from the outer gauzesthemselves, mapjKni out to show how they are rebuffed). Naturally. Kigs. 5 and 6—Mortons apparatus for determining excitation-potentials by thephotoelectric method. (Philosophical Magazine.) the arrangement of potentials in front of the electrode must be suchthat the emitted electrons are all drawn away from it, not drivenback onto it. The rate of emission of electrons, the photoelectriccurrent, may lie measured with an electrometer connected either to thesensitive electrode or tfi a gauze so placed as to gather in all theelectrons emitted from it. Figs, o and G, the latter of which shows a 286 BELL SYSTEM TECHNICAL JOURNAL completely equipped tube with filament at F, a row of targets whichcan be moved consecutively into place at T, and the photosensitiveelectrode at A with its gauze shields in front of it, come from the workof Horton, Andrewes and Davies. A tube designed and used byE. H. Kurth is shown in Fig. 7; the filament is seen in perspective atC, the target at 7, and the sensitive disc at D\ the family
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
