. A new thermo-electric fluid-meter and hot-wire anemometer. F TESTS; The curves for cells Nos. 6 and 8indicate the effect of increasing the filamenttemperature atove the reddening point. Aspreviously stated, this produces a permanentincrease in the filament resistance. It followsthat when the filament resistance is increased, theheater current must he decreased to obtain the newbalancing point C. See Curve Ho» 11, a?hisdecrease in current of course results in a smallerpotential across the drop resistance. It is interest-ing to note, that after the heating filament resistancehas changed, the c
. A new thermo-electric fluid-meter and hot-wire anemometer. F TESTS; The curves for cells Nos. 6 and 8indicate the effect of increasing the filamenttemperature atove the reddening point. Aspreviously stated, this produces a permanentincrease in the filament resistance. It followsthat when the filament resistance is increased, theheater current must he decreased to obtain the newbalancing point C. See Curve Ho» 11, a?hisdecrease in current of course results in a smallerpotential across the drop resistance. It is interest-ing to note, that after the heating filament resistancehas changed, the cell continues to function properlyexcept that a lower value of e. m, f, is obtained,assuming of course, that the drop resistance is notchanged. In the event of an accident of this naturethe standard e, m. f, may be restored to its originalvalue by adjusting the drop resistance. In conclusion, it is believed that thecharacteristics of standard thermoelectric celljustify its use in many measurements in whichprimary standard cells are now used. This cell has. 2S4 been successfully used with potentiometers designedfor thermocouple works and would seem to presentgreat advantages, as mentioned before, where relative-ly high or low temperatures are to be encountered. In the past few years several of thesepotentiometers have been in constant use, and havebeen operated by unskilled labor. During this periodno particular trouble has been experienced that couldbe charged to the standard cell. Several cells havebeen burned out through carelessness of the every case of a damaged cell it has been found thateither the galvanometer or the slide wire or both weredestroyed. Another great advantage embodied in thethermoelectric cell is the fact that a very lowresistance cell can be readily constructed. In factthe values given above are lower than that of theunsaturated, and decidedly lower than the saturatedWeston cell. That is a point which is of greatimportance in selecting a suita
Size: 1343px × 1860px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookidnewthermoele, bookyear1920
