D Arsonval galvanometer

The coil (wound on a light metal former) can be suspended by a fine strip of phosphor bronze between the pole pieces. Attached to this suspension is a small mirror which reflects on to a scale a beam of light which is focused upon it. An instrument of this kind is known as a D Arsonval galvanometer and is used in potentiometer circuits and various methods of measurement of resistance. 

The Cahn electrobalance is a sensitive, accurate, reliable, and easily operated balance which is based on a D Arsonval galvanometer, with the sample... 

Where measurements of current in massive structures having extremely low longitudinal resistances are required, and to avoid the errors referred to in the previous paragraph, a refinement of the zero-resistance ammeter is used. Instead of a voltmeter, a high-sensitivity D Arsonval galvanometer with a centre-zero scale is used. The connections remain essentially the same as those in Fig. 10.47, except that a reversing switch is incorporated so that the current 4 can be applied first in one direction and then in the other. 

The D Arsonval galvanometer plays a very important role in electrical measurements. A coil of wire located in a magnetic field produced by permanent magnets is mounted on low friction bearings (Fig. 10.14). Rotation is constrained by coil springs that also conduct current to and from the coil. A pointer attached to the coil moves across a scale that indicates rotary displacement proportional to the current (/), flowing through the coil. 

D Arsonval galvanometer — Historic moving-coil -> galvanometer where a rectangular metal coil is hanging between the horseshoes of a permanent magnet. 

Null point detection, also, could be achieved via the use of a sensitive galvanometer, such as the Deprez-d Arsonval, in conjunction with high cell resistances (100 to 1000 megohms). 

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