Photographic optics and colour photography [electronic resource] : including the camera, kinematograph, optical lantern, and the theory and practice of image formation (1909)
Johnson, G. Lindsay (George Lindsay), 1853-, Parsons, John Herbert, Sir, 1868-1957, donor, University College, London. Library Services · London : Ward & Co. · leaf 40
ont of a light, the latter will pass through the slits twice in each period (Fig. 24). Now the rate of vibration can be readily- ascertained either from the note, or the length of its prongs since the rate is a constant quantity. Hence the number of flashes per second can be found with great… … Fig. 24. — Electrically-driven Tuning-fork with Slits. taken for one dot to occupy the position of the next, is exactly- equal to the time between each successive flash of light. Let n = vibrations of the fork per second ; N = number of dots or geometrical angles round the disc ; s = number of…
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