The London, Edinburgh and Dublin philosophical magazine and journal of science . h the tween the through the Workingvolts of middle plate graded gal- Working middle plate graded gal- and positive vanometer volts of the and positive vanometer the lamp. electrode of in milli- lamp. electrode of in milli- the lamp. amperes. the lamp. amperes. 30 •6 •095 39 4-3 •761 32 1-1 •174 ;? 140 2-22 34 2-0 •317 40 5-1 •809 35 2-6 •412 ?5 18-1 2-87 36 3-2 •507 41 5-3 •841 37 3-9 •618 ty 18-4 2-91 38 4-3 •682 42 6-4 1-01 jj 4-5 •714 )? 20-0 3-17 jj 11-0 1-74 43 6-2 •983 V 22-0 3-49 These observations are plot
The London, Edinburgh and Dublin philosophical magazine and journal of science . h the tween the through the Workingvolts of middle plate graded gal- Working middle plate graded gal- and positive vanometer volts of the and positive vanometer the lamp. electrode of in milli- lamp. electrode of in milli- the lamp. amperes. the lamp. amperes. 30 •6 •095 39 4-3 •761 32 1-1 •174 ;? 140 2-22 34 2-0 •317 40 5-1 •809 35 2-6 •412 ?5 18-1 2-87 36 3-2 •507 41 5-3 •841 37 3-9 •618 ty 18-4 2-91 38 4-3 •682 42 6-4 1-01 jj 4-5 •714 )? 20-0 3-17 jj 11-0 1-74 43 6-2 •983 V 22-0 3-49 These observations are plotted in Curve No. 2, in which theabscissae represent the working volts of the lamp and the Edison Effect in Glow Lamps. 59 ordinates the current in milliamperes flowing through thegalvanometer connecting the positive electrode and the middleplate. It is seen that corresponding to any working pressureabove 38 volts for this lamp, which is equivalent to 4*2 wattsper candle-power, there are two possible values of the effective Table No. 2.—Curve No. 32 34 36 38 40 42 44Working Volts of Lamp. potential-difference between the middle plate and the positiveelectrode. As the working voltage of the lamp is graduallyraised, the reading of the galvanometer inserted between themiddle plate and positive electrode is also increased, but thereis a great tendency to jump from a certain low value to a 60 Prof. J. A. Fleming on the higher one, and this occurs when the working pressure of thelamp is preserved steady. There is also an effect producedby the presence of a magnet near the lamp bulb. When thecurrent is at the low value corresponding to any workingvoltage, the galvanometer reading does not seem to be per-ceptibly altered by bringing a magnet near the lamp, butwhen it is at its high value, the reading is sometimes increasedfor a little, showing a steady deflexion, and then immediatelyfalls to its low value. § 5. Experiment 2.—The difference of potential
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