. Motion picture electricity. n points, un-less some other element is introduced to counterbalancethis effect, or, in other words, put a check or limit on thecurrent flow. The element which in practice is used forthis purpose in connection with projector arc lamps, isthe resistance or rheostat, as it is usually called. For thepurpose of checking the current in series with the arc, arheostat composed or made of a material which will in-crease in resistance as the temperature of the resistance,or wire is increased. For a better understanding of theforegoing references I refer you to the accompan
. Motion picture electricity. n points, un-less some other element is introduced to counterbalancethis effect, or, in other words, put a check or limit on thecurrent flow. The element which in practice is used forthis purpose in connection with projector arc lamps, isthe resistance or rheostat, as it is usually called. For thepurpose of checking the current in series with the arc, arheostat composed or made of a material which will in-crease in resistance as the temperature of the resistance,or wire is increased. For a better understanding of theforegoing references I refer you to the accompanying il-lustrations. TO CIRCUIT- GLOWER rt MATCH Fig. 72 Fig. 72 shows a Nernst lamp glower connected to anelectric circuit with a lighted match below it, the flame ofwhich heats the glower so that it becomes a conductor, and MOTION PICTURE ELECTRICITY 133 Fig. 73 shows the glower in operation, in which conditionit would last only a second, because the current will crowdthrough it more and more, the hotter it gets, burning it. Fig. 73 out as shown in illustration Fig. 74. The correct methodof operation, in order to prevent the glower from admit-ting too much current, is to connect a ballast or a re- -to circuit- Fig. 74 sistance in series with the glower as illustrated in Fig. this instance the ballast is enclosed in a vacuumwithin a glass bulb, and the ballast wire, which is madeof a material like iron, operates at red heat.
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Keywords: ., bo, bookcentury1900, bookdecade1910, bookidmotionpictureele00hall
