Light, photometry and illumination : a thoroughly rev. ed. of ''Electrical illuminating engineering'' (1912)
Barrows, William Edward, 1878-1960 · New York ; London : McGraw-Hill Book Co. · leaf 180
lamp,because of the small size of the room, was reflected onto thescreen by means of another mirror, M. The illumination onthe side of the screen toward the arc lamp, being very intense,was reduced by means of a rotating disk provided with a largenumber of slots. LIGHT-FLUX CALCULATIONS 165 The… … Fig. 95.—The Mathews photometer. = distance from arc lamp to the photometer screen. = distance from standard to photometer screen. = reflection constant of the horizontal mirror. = transmission constant of clean glass.Ks = reflection constant of mirror of the standard.Ky, — transmission constant of…
Light · Photometry · Electric lighting
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