Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . Gauvan omete r Fig. 227.—Students Slide Wire Bridge. Complete connections for measuring the unknown resistance at D are depicted. The students Daniell cell and detector galvanometer are used. then the condition of balance is destroyed, the lamps at A are sub-jected to 125 volts and burn above c. p. while lamps at C are cut out ofcircuit and the wire 3-4 carries the current flowing through the lampsat A. This lamp chart should assist the student in understanding how thepotentials are
Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . Gauvan omete r Fig. 227.—Students Slide Wire Bridge. Complete connections for measuring the unknown resistance at D are depicted. The students Daniell cell and detector galvanometer are used. then the condition of balance is destroyed, the lamps at A are sub-jected to 125 volts and burn above c. p. while lamps at C are cut out ofcircuit and the wire 3-4 carries the current flowing through the lampsat A. This lamp chart should assist the student in understanding how thepotentials are balanced in the slide wire bridge and the Wheatstonebridge, | 250. 249. Construction and Use of Slide Wire Bridge.—A simple form of slide wire bridge for measuring resistance isdepicted in Fig. 227. A piece of German silver or platinoidwire, about No. 24, is stretched between binding posts, cd,mounted on a wooden base. Directly under the wire is apaper double scale about 22 inches long, graduated in 1000equal divisions with zero at either end, to facilitate takingreadings from either point, c or d,. MEASUREMENT OF RESISTANCE. 255 Strips of copper mounted on the base, support additionalposts for reception of the spool resistance terminals and serveto make electrical connections. The small letters and figuresindicate the same points on this bridge as shown in the dia-gram, Fig. 225, by which its principle was explained, ^j resistance spool, withcopper terminals, shownin detail in Fig. 228, andwound non-inductively,^f 299, is inserted in thebinding posts at A, , and corresponds to N(.,..,„„...,.the former resistance a-3. R«,StaNC£ 5p<»- s° The unknown resistance, FiS- 228.—Details of Resistance Spool o -, , -. , ,i and Slider. o-b, is connected to the posts at D. The battery is connected across points 1 and 2,as before, and one galvanometer terminal to post 3, theother galvanometer post is connected to the flexible wireslider shown in detai
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1901
