The Electric Bell
المؤلف:
GEORGE A. HOADLEY
المصدر:
ESSENTIALS OF PHYSICS
الجزء والصفحة:
P-370
2025-12-10
5
The common electric bell is an application of the electromagnet. When the button B is pressed, it closes the circuit, and the current enters by the + binding post; passes around the electromagnet, then to the post P (Fig. 1), through which runs a pin that makes contact with the armature of the magnet by means of a light spring, then along the spring S to the - binding post. In bells having an iron base the base itself is made a part of the circuit. As soon as the current passes, the armature of the electromagnet is attracted and the current is broken at. P. When this happens the magnet no longer attracts the armature, and the spring S carries it back against the post P, again making the circuit. This causes the bell to ring automatically as long as the button is pushed. When two or more bells are to be rung from a single push button, they should be coupled in parallel, as they will not ring well in series unless they strike at exactly the same rate (Fig. 2).
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