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#Mon Aug 09 12:05:15 CEST 2010
Text__hyOIUKOdEd-WfYQ0GneCwQ_text=<p>In 1820, Hans Christian \u00D8rsted described the deflection of a magnetized needle caused by an electric current. This effect can be used to measure electrical currents. Two oppositely poled needles counteract the disturbing influence of the Earth\u2019s magnetic field, thus the name <q>astatic needle pair</q>. This example is an instrument built for laboratory purposes; the serial production of galvanometers first began in the 1870s.</p>
Text__hyOIUKOdEd-WfYQ0GneCwQ_title=Galvanometer with Astatic Needle Pair