The Physical Review Volume 7

The Physical Review Volume 7

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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. 1916 edition. Excerpt: ...metal the smaller is the value of v at which it becomes photo-sensitive, a conclusion however which later researches on the non-alkaline metals seemed for years to contradict. 1 Lenard (Ann. d. Phya. (4), 8, 149, 1902) discovered a maximum velocity though he did not find the effect of frequency upon it. Ann. d. Phys., 45, 1120, 1914 and 45, p. 961. Wied. Ann., 43, 225, 1891. 4..... During the ten years which have elapsed since Einstein set up his equation the fifth of the above assertions has never been tested at all, while the third and fourth have never been subjected to careful experimental test under conditions which were even claimed to permit of an exact and definite answer, nor indeed can they be so subjected without simultaneous measurements in vacuo of both contact potentials and photo-potentials in the case of metals which are sensitive throughout a long range of observable frequencies. In making this statement I am not underrating at all the exceptionally fine work of Richardson and Compton,1 who in common with most other observers interpreted their results in terms of Einstein's equation, but who saw the significance of that equation much more clearly than most of their predecessors had done. I am merely calling attention to the fact that the slope mentioned in (3) and the intercept mentioned in (4) cannot possibly be determined with any approach to certainty unless the region of wave-lengths open to study is larger than it is in the case of any save the alkali metals, and also, in the case of (4) unless simultaneous measurements are made in vacuo upon photo-potentials and contact E.M.F.'s. The fact that Richardson and Compton's slopes vary by more than 60 per cent. is sufficient evidence of the correctness of this statement. Also more

Product details

  • Paperback | 226 pages
  • 189 x 246 x 12mm | 413g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236581466
  • 9781236581464