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Instruments Used in Measurements; Galvanometers

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-380

2025-12-11

381

A galvanometer is an instrument that shows the intensity of a current passing through it, by the amount of the deflection of a needle or other moving part. It is calibrated by determining experimentally the relation between the current and the corresponding deflection, and indicating this on a graduated scale. A galvanometer of small resistance, if calibrated to read in amperes, is called an ammeter. If the resistance of a galvanometer is known, the potential difference that sends the current can be readily determined. A galvanometer of high resistance, calibrated to read directly in volts, is called a voltmeter.

The detector galvanometer (Fig. 1), or galvanoscope, is used rather to show the presence of a current than to measure its intensity. A simple form can be made by using a small compass for the needle, setting this in a block, and winding a few turns of insulated wire around it. By connecting the ends of the coil to binding posts, the instrument is completed and will answer for many experiments.