Bulletin of the Bureau of Standards Volume 3

Bulletin of the Bureau of Standards Volume 3

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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. 1907 edition. Excerpt: ... to bending. At speeds of 600 or 700 r. p. 1n., when the filaments were well over against the glass, the decrease in candlepower reached a value as high as 4 per cent for one of the lamps; but whenever the change i11 candlepower was large there was always a very appreciable change in resistance, indicating that the change in candlepower was due probably, to a large extent, to a cooling of parts Of the filament. In Fig. I, lamp No.6 is shown both when new and after having touched the bulb and burned out. At the high speed of 675 r. p. n1. one loop was short-circuited by the next and the filament burned out at the point of contact. From a consideration of all the data given in the preceding para graphs it is seen that the maximuin error observed, due to a bending of the filament, was 11ot iii any case greater than 1.5 per cent, pr0vided the filament did not touch the bulb, even though the filament was bent so as almost to touch the bulb. The speed of rotation necessary to force the filament against the bulb was not less than 600 r. p. 111. except for the special 32-cp 220-volt lamps without anchors, and for these it was about 400-450 r. p. In. For 111ost common types of lamps the speed would be much higher than 600 r. p. 111., and it is probable that for some types a rupture of the filament would occur before the filament would touch the bulb. VVhen the filament touches the bulb changes in candlepowel' Of as 1nuch as 6 or 7 per cent may take place, but as these large changes are always accompanied by relatively large changes in resistance, it is probable that they are due to a cooling of the filament owing to the contact with the glass. EFFECT OF BENDING. As explained in detail in the original paper referred to above, the difference...show more

Product details

  • Paperback | 168 pages
  • 189 x 246 x 9mm | 313g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236974867
  • 9781236974860