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The Fall of Potential along a Conductor

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-385

2025-12-11

525

Demonstration. - Stretch a high-resistance wire 1 m. long on a board between two binding posts A and B (Fig. 1).

 Climax wire No. 18, or German silver No. 24, will answer. Couple a half dozen or more cells to the binding posts with a snap switch in the circuit. Couple one terminal of a low-reading voltmeter to A and the other terminal to a wire that can be touched to the wire AB at any point. On sending the current through AB and touching the voltmeter wire to B the voltmeter reading will show the fall of potential for the whole length of AB. Touch the wire at the points 9, 8, 7, and the reading of the voltmeter will be nine tenths, eight tenths, and seven tenths, respectively, of the reading for AB. In order to prevent the polarization of the cells the current should be left on only just long enough to get each reading.

It will be found that the fall of potential is directly proportional to the length of the wire.