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Two Kinds of Electrification

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-319

2025-11-29

574

We have seen that the glass rod, the sealing wax, and the ebonite rod all attract other bodies when electrified. Their action upon one another may be seen in the following:

Demonstration. - Electrify a glass rod and suspend it in the wire stirrup. Bring a wooden rod near it, and it will be attracted. Bring an electrified ebonite rod near it, and it will be attracted more than before. Now electrify a second glass rod and bring it near the end of the suspended rod, and repulsion takes place. Suspend the electrified sealing wax in the stirrup and hold near it a second electrified stick of sealing wax, and repulsion takes place. Hold near it an electrified glass rod, and it is attracted. Hold near it an electrified ebonite rod, and it is repelled.

FIG .1

We find that the electrified glass rod and sealing wax have apparently the same effect upon an unelectrified body, but act differently upon one that is electrified. When this difference was first observed, the kind of electrification produced on a glass rod by rubbing with silk was called vitreous electricity, and that produced on sealing wax by rubbing it with flannel, resinous electricity. These are now called positive or + and negative or -, respectively. For the sake of convenience, these states of electrification will be spoken of as positive and negative electricity.