Immagini

DESCRIPTION

Exhibit 753 is a Wheatstone bridge used to measure with high precision an unknown resistance by comparing it with a known resistance. This apparatus consists of a metallic wire of uniform diameter 0,7 mm and 120 cm long mounted on a wood base along with a copper bar, a metric scale and the mercury contact terminals used to realize the circuit shown in design-1. The circuit is activated by the battery E.

There is a cursor C that makes contact on the uniform wire at a position legible on the metric scale. The two parts of the wire constitute two arms of the bridge, while the other two resistances R_x (ignota) eand R (nota) are inserted in the terminals A and D. Between B and the cursor C there is inserted a galvanometer G.

To utilyze the apparatus one moves the cursor C along the wire until the galvanometer indicates zero current.

Assuming that the wire has constant resistance per unit length, one has

BIBLIOGRAPHY

• [1] E.Perucca," Guida Pratica per Esperienze Didattiche di Fisica Sperimentale", Zanichelli Editore.1937. § 478, pag. 561.
• [2] Walter A. Schneider, Lloyd B. Ham, "Experimental Physics for Colleges", The Macmillan Company, New York, 1932. Pag.160. Vedi: URL [ http://archive.org/details/experimentalphys033058mbp ]
• [3] A. Ganot,"Elementary Treatise on PHYSICS Experimental and Applied", Longman, Green, and CO. 1902. Pag 934.

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