. The study of the velocity of electrons in the photo-electric effect, as a function of the wave-lengths of the light. intensity of the light. Two other recent papers makefurther measurements important. J. R. Wright , finds that there isa decided maximum in the curve representing potential and frequencyin the case of zinc; and R. Pohl and P. Pringsheim^ find that thereare to different photo-electric effects in the alhali metals, theordinary and the effect. They measured, however, the photo-electric currents, and not the equilibrium potential acquired by theaetals. It is therefore im
. The study of the velocity of electrons in the photo-electric effect, as a function of the wave-lengths of the light. intensity of the light. Two other recent papers makefurther measurements important. J. R. Wright , finds that there isa decided maximum in the curve representing potential and frequencyin the case of zinc; and R. Pohl and P. Pringsheim^ find that thereare to different photo-electric effects in the alhali metals, theordinary and the effect. They measured, however, the photo-electric currents, and not the equilibrium potential acquired by theaetals. It is therefore important to ascertain whether there aretwo different effects to be found in this equilibrium potential,v.:.ether there is a maximum, or whether the potential increases con-tinuously throughout the range of the visible light. Finally theinfluence of the temperature on the equilibrium potential has to bedetermined. 1. , Vol. 33, 1, 1911, 2. R. Pohl & P. Pringsheim, Verhandlungen, , 12,, 1910; 4 R, Pohl, Verhandlungen, 11, 7151909; 13, 961, 6 Description of Apparatus and Method, The arrangement of the essential parts of the apparatus used inthis research is shown in Fig. I, The source of light is a carbonarc L . The light passes through a slit and system of lenses whichgives a beam of parallel light upon the prism P , which is capableof rotation, thus providing for an intense source of light, whichaft»r passing through the prism, falls upon the slit S of a lighttight box containing the photo-electric cell. By rotating the prismP any desired wave length can be made to pass through the slit 8 andfall upon the photo-electric metal C. The illuminated electrode Cof the cell is connected through a key K and commutator R to a pairof quadrants of a Polazalek electrometer E. Statio charges wereavoided by having the cell, connections, keys and measuring instru-ment, which were manipulated from a distance, all inside o
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectlight, bookyear1912
