Immagini

DESCRIPTION

Exhibit 469 is a commutator switch which can invert the direction of a current or change the connections of two or more electrical circuits. The connections are changed by moving mobile elements which open some internal connections when closing others, all of which remain connected to the permanent external terminals. In this switch, made in the physics institute, the internal contacts are made using mercury in small cups. There are three pairs of cups, one central (A and B) and two lateral ones (C and D, E and F)

The functioning is most clearly illustrated in the image: in the illustrated position; B to F to C, A to E to D. In the switched position; B to D to F, A to C to F. The lengths of the contacts arms are such that contact can be made with only one lateral pair at a time. This type of switch is called a rocker (or swinger) because it rocks or swings back and forth (see exhibit 137).

BIBLIOGRAPHY

• [1] Stewart Balfour, Gee Haldane," Lessons in Elementary practical physics", Vol. II, London 1887

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