The London, Edinburgh and Dublin philosophical magazine and journal of science . rminal of the galvanometer wasconnected to one terminal of a condenser of 5 microfaradscapacity. The other terminal of the condenser was connectedby a wire to the gas pipes of the laboratory. The lamp wasactuated by secondary batteries (see fig. 17) not very wellinsulated. If the condenser was charged to a potential of50 volts so that the plate next the galvanometer was posi-tively charged, then this positive charge was instantly dis-charged when the carbon was rendered incandescent. If,however, the plate of the c
The London, Edinburgh and Dublin philosophical magazine and journal of science . rminal of the galvanometer wasconnected to one terminal of a condenser of 5 microfaradscapacity. The other terminal of the condenser was connectedby a wire to the gas pipes of the laboratory. The lamp wasactuated by secondary batteries (see fig. 17) not very wellinsulated. If the condenser was charged to a potential of50 volts so that the plate next the galvanometer was posi-tively charged, then this positive charge was instantly dis-charged when the carbon was rendered incandescent. If,however, the plate of the condenser in connexion with themiddle plate through the galvanometer was charged negativelythe condenser was not discharged when the lamp was illumi- 90 Prof. J. A. Fleming on the nated by rendering its carbon incandescent. It is a very-striking experiment to see a condenser charged with thisamount (250 microcoulombs) of electricity instantly dischargedwhen its positive coating is brought into connexion with themiddle plate of such a lamp. The discharge may be brought Fte. 70 SEcY. BATTERY To EARTH about either by joining up the positive side of the condenserto the middle plate first, and then rendering the carbon of thelamp incandescent by switching on the lamp, or the lampmay be first of all illuminated and then the junction of thecondenser effected. In both cases the middle plate whenpositively electrified is instantly discharged. It was found that if the lamp carbon is rendered incandescentbva highly insulated secondary battery then in order to producethe discharge, the plate of the condenser not in connexionwith the middle plate, and which is negatively charged, mustbe somewhere connected with the battery circuit. It doesnot matter, however, whether the wire from the negativeside of the condenser is in connexion with the positive or thenegative pole of the secondary battery actuating the lamp ;all that is necessary is that the negative side of the condensershould be in
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Keywords: ., bookcentury1800, bookdecade1840, bookidlondon, booksubjectscience
