Some Contributions from the Laboratory of Physics of the University of Illinois, Urbana, Illinois; For 1914-1919 Volume 2

Some Contributions from the Laboratory of Physics of the University of Illinois, Urbana, Illinois; For 1914-1919 Volume 2

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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. 1914 edition. Excerpt: ...of known light-intensities, keeping conditions the same as before the nicol was rotated through various angles, observations were taken in adjacent quadrants and the mean taken to correct for any asymmetry of the nicols with respect to the axis of rotation. These mean deflections were then plotted against the squares of the cosines of the angles. The light-intensities corresponding to the observed deflections for the reflected light could then be read on the curve, giving the reflecting powers directly. A calibrationcurve was thus obtained for every series of observations. The true relation between the light-intensity and photo-electric current can be determined only under the imposition of proper experimental conditions. In the present investigation, the interest lay not so much in the relation between the current and the lightintensity, as in the relation between the light-intensity and resulting electrometer deflections. Experimental conditions were always employed such as to give greater stability and accuracy to the observations. Consequently as low a voltage as possible was used on the needle. Also, in part of the work, as previously mentioned, the first throw of the needle was employed. For these reasons, it is not safe to assume that the photo-electric current is proportional to the electrometer deflections. Hence the curves between electrometer deflections and light-intensity are not to be assumed as being relations between photo-electric current and light-intensity. They are merely to be regarded as calibrationcurves. In general the curves approximated to straight lines, being either slightly convex or concave to the illumination-axis, depending upon the experimental conditions imposed. No theoretical value is assigned to these curves, ..
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Product details

  • Paperback | 60 pages
  • 189 x 246 x 3mm | 127g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236576624
  • 9781236576620