The Elements of Physics (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1892 Excerpt: ... excited tube, remove the wire, handling it with some non-conductor. The electroscope remains charged. On testing it, it will be found to be positive. A similar test made of the ball will show that it is negatively charged. Repeat the experiment without removing the connecting wire. No signs of electrification exist on removing the excited tube. Hence, we learn two things: (1) When an electrified body is brought near an object it induces the opposite kind of electricity on the side next it and the same kind, on the remote side; (2) the two kinds of electricity are developed in equal quantities. 275. Attraction explained.--Since an electrified body induces the opposite kind of electricity on the near side of a neighboring object, an attraction will, in consequence, exist between them. If the neighboring object were a non-conductor, the electrical separation would be prevented, and no attraction would take place. This may be proved by suspending a small ball of sealing-wax by a silk thread and bringing near it an electrified glass tube. 276. Charging an Electroscope by Induction.--Exp.--Hold one finger on the ball of the electroscope and bring near it an electrified glass tube. Remove the finger before taking away the rod and the electroscope will be charged. Explain. What kind of electricity will then be in the electroscope? How can you modify the intensity of the charge? 277. Inductive Capacity.--Exp.--Suspend an electrified brass ball above an electroscope, and distant far enough to produce only a slight effect on the leaves. Take a cake of paraffin or sulphur whose thickness is a little less than the distance between the ball and the electroscope, pass a gas flame over its surface to remove all traces of electrification, and insert it between the ball and...