Immagini

DESCRIPTION

Exhibit 561 is a DC moving coil milliammeter with a 5 mA range, mounted vertically on a wood board supported on an H-shaped wood base. The terminals are located on the sides and are identified by the indications: + e - .

The instrument contains various shunts which extend the range to 25 or to 50 mA, by using a selector switch located in the lower section. The effective shunt choice is shown in a small window below the dial.

The principle of operation of this instrument is similar to that of a moving coil galvanometer with the difference that the moving part is mounted on a pivot and the restoring force of the torsional wire is substituted by a spring. The current value is indicated by a pointer, attached to the moving coil, which rotates over the printed dial.

The sensitivities corresponding to the different current values are:

for -------------- sensitivity
5 mA ------------ 0,1 mA
25 mA ---------- 0,5 mA
50 mA ---------- 1,0 mA

ISCRIZIONI

1. Sul quadrante è impresso un piccolo simbolo dello strumento elettrodinamico con la scritta MILL-AMP; sotto la scala c'è il numero: 51838.

BIBLIOGRAPHY

• [1] Franco Erdas, Giuseppe Baggiani, "Gli Strumenti del Museo di Fisica, "Elettromagnetismo", Università degli Studi di Cagliari,Pagina 61.
• [2] P. Fleury, J.P. Mathieu, "Correnti variabili Onde elettromagnetiche", Zanichelli Bologna. §11.11, Pagina 325.

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