» Siemens Electrodynamometer (0643)

Immagini

DESCRIPTION

Exhibit 643 is a Siemens Electrodynamometer mounted on a wood support in the form of an inverted "U" on a rectangular base with leveling screws. There is also a plumb line for verticality (photo 3).

To measure alternating currents, one cannot use a galvanometer because the rapid equal and opposite current impulses leave the pointer in equilibrium.

This electrodynamometer according to the Siemens catalog can reveal and measure both alternating and direct currents. To measure strong currents, connect to terminals 1 and 3; for weak currents connect to terminals 1 and 2.

Windings 'R' and 'S' are fixed vertically. The movable coil 'M' is suspended by a silk thread attached to the top screw and ends with two steel contacts that enter in the cups 'U' and 'V' (connected to terminal 1). This coil is maintained vertical by a bronze helical spring that surrounds the silk thread. In this condition the index I of the coil 'M' points to zero on the dial graduated in degrees when there is no current.

ISCRIZIONI

Siemens & Halske
Berlin
No. 2405

BIBLIOGRAPHY

[1] Catalogo della ditta Lenoir & Forster Wien, volume II Fisica, 1884, pg. 730 (num. Cata. 7217)
[2] Giovanni Boato ,Giuseppe Bruzzaniti,"Strumenti Nella Fisica dell'Ottocento", Università degli studi di Genova. pagina 59
[3] Oreste Murani,"Trattato Elementare di Fisica", Vol II, Hoepli , Milano 1906. pagina 507.

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