Circular of the Bureau of Standards Volume 41-48

Circular of the Bureau of Standards Volume 41-48

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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. 1913 edition. Excerpt: ... high tensile strength copper-clad steel is used. Samples are submitted in the form of wires or rods and are tested for conductivity, resistance-temperature coefficient, resistance and inductance to alternating current or tensile strength. Closely related to conductor materials are resistance materials, including such alloys as manganin, constantan, and therlo, for use chiefly in electrical instruments and meters; calorite and other alloys are especially adapted to electric heating devices. Such materials are tested for resistivity, temperature coefficient, and thermal electromotive force against copper. Melting points are also determined when desired. Among insulating materials for the testing of which the Bureau is partially prepared may be mentioned rubber (as a covering for wires and cables), insulating cloth, paper, tape and varnish, vulcanized fiber, pressboard, and transformer oils. Iron and steel, the only magnetic materials of commercial importance, are tested for two general magnetic properties: First, the ballistic test, which gives the permeability data of interest when the material is used for direct-current electromagnets; and, second, the loss test. This latter determines the total losses occurring in a definite amount of the material when subjected to alternating magnetization at stated frequencies and flux densities. (See Circulars Nos. 6, 17, 20, 21, 31, 36, and 37.) B. OPTICAL MATERIALS The following optical tests of materials will be made as desired: 1. Identification of glasses, crystals, and fluids by a determination of the refractive index to the fourth decimal place. A polished plane surface of 20 mm on a solid or a few drops of a fluid are sufficient. 2. Refractive index and dispersion of glasses, crystals, and...show more

Product details

  • Paperback | 330 pages
  • 189 x 246 x 18mm | 590g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236743865
  • 9781236743862