This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 edition. Excerpt: ...as we press the button, this process continues, producing what sounds like a continuous jingle; in reality the clapper strikes the bell every time a current passes through the electromagnet. The push button.--The push button is an essential to the operation of every electric bell, because without it ...
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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 edition. Excerpt: ...as we press the button, this process continues, producing what sounds like a continuous jingle; in reality the clapper strikes the bell every time a current passes through the electromagnet. The push button.--The push button is an essential to the operation of every electric bell, because without it the bell either would not ring at all, or would ring incessantly until the cell was exhausted. When the push button is free, as in Figure 90, the cell terminals are not connected in an unbroken path, and hence the current does not flow. When, however, the button is pressed, the current has a complete path, provided there is the proper connection at P (Fig. 89). That is, the pressure on the push button permits current to flow to the bell. The flow of this current depends solely upon the connection at P, which is alternately made and broken, and in this way produces sound. Fig. 8q.--The electric bell. The sign " Bell out of order" is usually due to the fact that the battery is either temporarily or permanently exhausted. If wet cells are used, the liquid may dry up in warm weather and stop the current or the liquid may have eaten up all the zinc. These diff1culties may be remedied by adding water or by renewing the zinc. If dry cells are F1o. 90.-Push button. used, there is no remedy except in the purchase of new cells. How electricity may be lost to use.--In the electric bell, we saw that an air gap at the push button stopped the flow of electricity. If we cut the wire connecting the poles of a battery, the current ceases because an air gap intervenes and electricity does not readily pass through air. Many substances besides air stop the flow of electricity. If a strip of glass, rubber, mica, or paraff1n is introduced anywhere in a...
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Seller's Description:
Fair. Cracked at both hinges, webbing exposed, pages secure. Marking inside both covers and a few places within. Age-toned, some staining. Cover scuffed, stained, bumped corners, exposed boards. Spine cover faded. No dj. Your purchase benefits world-wide relief efforts of Mennonite Central Committee.