File:X-ray manual - U.S. Army (1917) (14570591800).jpg

Identifier: xraymanualusarmy00unit (find matches)
Title: X-ray manual : U.S. Army
Year: 1917 (1910s)
Authors: United States. Surgeon-General's Office American Roentgen Ray Society
Subjects: X-rays Fractures Teeth Chest Heart Radiography
Publisher: New York : Middleditch
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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lapse ofsome time. If we could count the number of electronspassing on to A per second, say N, we would call Nethe current passing through G. An electric current maythen be regarded as a measure of the number of electronspassing per second. It must be observed that after Aand B are charged as highly as is possible for the particu-lar generator, there will be no further current, but thevoltage is present. We may have voltage existing andno current, but never a current without some voltage. Conductors. It requires but little voltage to move a big supply ofelectrons through some materials, while with others avery great voltage will cause but little electron move-ment. The former are named conductors; the latter, in-sulators. Note carefully that the difference is one of de-gree, and that perfect insulators do not exist so far ashigh applied voltage is concerned. Thus, dry clean glassmay be considered an insulator for moderate voltages,but may conduct to a considerable extent at high volt-
Text Appearing After Image:
Fig. 1. Generator on open circuit.xraymanualusarmy00unit

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